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Sandhill crane

The sandhill crane (Antigone canadensis) is a species of large crane of North America and extreme northeastern Siberia. The common name of this bird refers to their habitat such as the Platte River, on the edge of Nebraska's Sandhills on the American Great Plains. Sandhill cranes are known to frequent the edges of bodies of water. The central Platte River valley in Nebraska is the most important stopover area for the nominotypical subspecies, the great sandhill crane (A. c. canadensis), with up to 450,000 of these birds migrating through annually.

Taxonomy
In 1750, English naturalist George Edwards included an illustration and a description of the sandhill crane in the third volume of his A Natural History of Uncommon Birds. He used the English name "The Brown and Ash-colour'd Crane". Edwards based his hand-coloured etching on a preserved specimen that had been brought to London from the Hudson Bay area of Canada by James Isham. When in 1758 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the tenth edition, he placed the sandhill crane with herons and cranes in the genus Ardea. Linnaeus included a brief description, coined the binomial name Ardea canadensis, and cited Edwards' work.

The sandhill crane was formerly placed in the genus Grus, but a molecular phylogenetic study published in 2010 found that the genus, as then defined, was polyphyletic. In the resulting rearrangement to create monophyletic genera, four species, including the sandhill crane, were placed in the resurrected genus Antigone that had originally been erected by the German naturalist Ludwig Reichenbach in 1853.

The specific epithet canadensis is the modern Latin word for "from Canada".

Five subspecies are recognised:

 * A. c. canadensis (Linnaeus, 1758) – northeast Siberia through Alaska and north Canada to Baffin Island
 * A. c. tabida (Peters, JL, 1925) – south Canada and west, central United States
 * A. c. pratensis (Meyer, FAA, 1794) – Georgia and Florida
 * A. c. pulla (Aldrich, 1972) – Mississippi
 * A. c. nesiotes (Bangs & Zappey, 1905) – Cuba and Isla de la Juventud (Isle of Pines)

Description
Adults are gray overall; during breeding, their plumage is usually much worn and stained, particularly in the migratory populations, and looks nearly ochre. The average weight of the larger males is 4.57 kg, while the average weight of females is 4.02 kg, with a range of 2.7 to 6.7 kg across the subspecies. Sandhill cranes have red foreheads, white cheeks, and long, dark, pointed bills. In flight, their long, dark legs trail behind, and their long necks keep straight.

Immature birds have reddish-brown upperparts and gray underparts. The juveniles do not have the characteristic red foreheads, making it possible to distinguish the children from the parents, even when they are the same height.

The sexes look alike. Sizes vary among the different subspecies; the average height of these birds is around 80 to 136 cm. Their wing chords are typically 41.8 - 60 cm, tails are 10 - 26.4 cm, the exposed culmens are 6.9 - 16 cm long, and the tarsi measure 15.5 - 26.6 cm. Wingspan is 78.7 in (200 cm).

These cranes frequently give a loud, trumpeting call that suggests a rolled "r" in the throat, and they can be heard from a long distance. Mated pairs of cranes engage in "unison calling". The cranes stand close together, calling in a synchronized and complex duet. The female makes two calls for every one from the male.

Sandhill cranes' large wingspans, typically 1.65 to 2.30 m, make them very skilled soaring birds, similar in style to hawks and eagles. Using thermals to obtain lift, they can stay aloft for many hours, requiring only occasional flapping of their wings, thus expending little energy. Migratory flocks contain hundreds of birds, and can create clear outlines of the normally invisible rising columns of air (thermals) they ride.

Sandhill cranes fly south for the winter. In their wintering areas, they form flocks over 10,000. One place this happens is at Bosque del Apache National Wildlife Refuge, 100 miles south of Albuquerque, New Mexico. An annual Sandhill Crane Festival is held there in November.

Fossil record
Sandhill cranes have one of the longest fossil histories of any extant bird. A 10-million-year-old crane fossil from Nebraska is said to be of this species, but this may be from a prehistoric relative or ancestor of sandhill cranes, and not belong in the genus Grus. The oldest unequivocal sandhill crane fossil is 2.5 million years old, older by half than the earliest remains of most living species of birds, primarily found from after the Pliocene/Pleistocene boundary some 1.8 million years ago. As these ancient sandhill cranes varied as much in size as present-day birds, those Pliocene fossils are sometimes described as new species. Grus haydeni may have been a prehistoric relative, or it may comprise material of a sandhill crane and its ancestor.

Subspecies and evolution

Sandhill cranes vary considerably in size (much of which is clinal) and in migratory habits. A female of A. c. canadensis averages 3.46 kg, 94 cm in length, and has a wingspan of 1.6 m. A male of A. c. tabida averages 5 kg, 119 cm in length, and has a wingspan of 2.12 m. The southern subspecies (along with A. c. rowani) are intermediate, roughly according to Bergmann's rule.

Three subspecies are resident: A. c. pulla of the Gulf Coast of the U.S., A. c. pratensis of Florida and Georgia, and A. c. nesiotes of Cuba. The northern populations exist as fragmented remains in the contiguous U.S. and a large and contiguous population from Canada to Beringia. These migrate to the Southwestern United States and Mexico. These cranes are rare vagrants to China, South Korea, and Japan and very rare vagrants to Western Europe.

Six subspecies have been recognized in recent times:
 * Lesser sandhill crane, A. c. canadensis
 * Cuban sandhill crane, A. c. nesiotes – ESA: endangered
 * Florida sandhill crane, A. c. pratensis
 * Mississippi sandhill crane, A. c. pulla – ESA: endangered
 * Canadian sandhill crane, A. c. rowani
 * Greater sandhill crane, A. c. tabida

The Florida sandhill crane was listed as EC or easily confused to facilitate an attempted reintroduction of the whooping crane (Grus americana) into Florida. The attempt failed, but the listing remained. The current list of endangered subspecies includes only two birds, A. c. nesiotes and A. c. rowani, with A. c. pratensis no longer listed. Sandhill cranes occur in pastures, open prairies and freshwater wetlands in peninsular Florida from the Everglades to the Okefenokee Swamp.

Some authorities no longer recognize Canadian sandhill crane as a distinct subspecies, as insignificant genetic differentiation and minimal morphological differentiation exist between it and greater sandhill crane. The others can be somewhat more reliably distinguished in hand by measurements and plumage details, apart from the size differences already mentioned. Unequivocal identification often requires location information, which is often impossible in migrating birds.

Analysis of control region mtDNA haplotype data shows two major lineages. The Arctic and the subarctic migratory population includes the lesser sandhill cranes. The other lineages can be divided into a migratory and some indistinct clusters which can be matched to the resident subspecies. The lesser and greater sandhill cranes are quite distinct, their divergence dating to roughly 2.3–1.2 million years ago, some time during the Late Pliocene or Early Pleistocene. Glaciation seemingly fragmented off a founder population of lesser sandhill cranes, because during each major ice age, its present breeding range was frozen year-round. Still, sandhill cranes are amply documented from fossil and subfossil remains right to the modern era. Conceivably, they might be considered distinct species already, a monotypic G. canadensis and the greater sandhill crane, G. pratensis, which would include the other populations.

The scant differences between southern Canadian and western U.S. populations appear to result from genetic drift, due to the recent reduction in population and range fragmentation. Until the early 20th century, the southern migratory birds occupied a much larger and continuous range. Thus, the subspecies A. c. rowani may well be abandoned.

The two southern U.S. resident populations are somewhat more distinct. The Cuban population has been comparatively little studied, but appears to have been established on the island for a long time. They and the migratory greater sandhill cranes proper may form a group of lineages that diverged much later from a range in the southern U.S. and maybe northern Mexico, where they were resident. The southern migratory population would then represent a later re-expansion, which (re-)evolved their migratory habits independent from the northernmost birds, the geographically separated populations expanding rapidly when more habitat was available as the last ice age ended.

Behavior
Sandhill cranes are fairly social birds that usually live in pairs or family groups through the year. During migration and winter, unrelated cranes come together to form "survival groups" that forage and roost together. Such groups often congregate at migration and winter sites, sometimes in the thousands.

Diet
Sandhill cranes are mainly herbivorous, but eat various types of food, depending on availability. They often feed with their bills down to the ground as they root around for seeds and other foods, in shallow wetlands with vegetation or various upland habitats. Cranes readily eat cultivated foods such as corn, wheat, cottonseed, and sorghum. Waste corn is useful to cranes preparing for migration, providing them with nutrients for the long journey. Among northern races of sandhill cranes, their diet is most varied, especially among breeding birds. They variously feed on berries, small mammals, insects, snails, reptiles, and amphibians.

Breeding
Sandhill cranes raise one brood per year. In nonmigratory populations, laying begins between December and August. In migratory populations, laying usually begins in April or May. Both members of a breeding pair build the nest using plant material from the surrounding area. Nest sites are usually marshes, bogs, or swales, though occasionally on dry land. Females lay one to three (usually two) oval, dull brown eggs with reddish markings. Both parents incubate the eggs for about 30 days. The chicks are precocial; they hatch covered in down, with their eyes open, and able to leave the nest within a day. The parents brood the chicks for up to three weeks after hatching, feeding them intensively for the first few weeks, then gradually less frequently until they reach independence at 9 to 10 months old.

The chicks remain with their parents until one to two months before the parents lay the next clutch of eggs the following year, remaining with them for 10–12 months. After leaving their parents, the chicks form nomadic flocks with other juveniles and nonbreeders. They remain in these flocks until they form breeding pairs between two and seven years old.

Predators
As a conspicuous ground-dwelling species, sandhill cranes are at risk from a few predators. Corvids, such as ravens and crows, gulls, jaegers, raptors and mammals such as foxes, coyotes and racoons feed on young cranes and eggs. In Oregon and California, the most serious predators of chicks are reportedly coyotes, ravens, raccoons, American mink, and great horned owls, roughly in descending order. Cranes of all ages can be hunted by both North American species of eagles, bobcats, and possibly American alligators. Additionally, there is a report that even a much smaller peregrine falcon has successfully killed a 3.1 kg adult sandhill crane in a stoop. In New Mexico, humans hunt them with a permit granted in a lottery draw during late fall. There are a total of 17 states that allow hunting of Sandhill Cranes.

Sandhill cranes defend themselves and their young from aerial predators by jumping and kicking. Actively brooding adults are more likely to react aggressively to potential predators to defend their chicks than wintering birds, which most often normally try to evade attacks on foot or in flight. For land predators such as dogs, foxes, and coyotes, they move forward, often hissing, with their wings open and bills pointed. If the predator persists, the crane stabs with its bill and kicks. They can even kill predators by piercing through the skull with their sharp beak, and even coyotes can be killed.

Mainland North America
In the 1930s, sandhill cranes were generally extirpated east of the Mississippi River, but their populations have recovered, with an estimated 98,000 in the region in 2018, a substantial increase over the previous year. Although sandhill cranes are not considered threatened as a species, the three southernmost subspecies are quite rare. Resident populations, not migratory birds, cannot choose secure breeding habitat. Many subpopulations were destroyed by hunting or habitat change. The greater sandhill crane proper initially suffered most; by 1940, probably fewer than 1,000 birds remained. Populations have since increased greatly again. At nearly 100,000, they are still fewer than the lesser sandhill crane, which, at about 400,000 individuals continent-wide, is the most plentiful extant crane.

Some migratory populations of sandhill cranes face population threats due to interspecies competition with snow geese. Since the 1990s, snow geese have eaten waste corn on which the cranes also rely prior to migration. Sandhill crane populations are also threatened by hunting. Hunting cranes is legal throughout the states of the Central Flyway, from the Dakotas and Wyoming south to Oklahoma and Texas. Nebraska is the sole state along the Central Flyway where hunting cranes is illegal. Despite losses from hunting, interspecies competition and other pressures such as habitat loss, the species has expanded its range. Since the early 2000s, the sandhill crane has expanded both its winter (nonbreeding) and breeding ranges northward, including into upstate New York. In the 21st century, parts of the Midwestern United States have seen an extensive rebound of the species.

The transplantation of wild birds and introduction of captive-reared birds into suitable low-population areas have been called viable management techniques.

The Mississippi sandhill crane has lost the most range; it used to live along most of the northern Gulf of Mexico coast, and its range was once nearly parapatric with that of its eastern neighbor. As of 2013, about 25 breeding pairs exist in an intensively managed population. The Mississippi Sandhill Crane National Wildlife Refuge—established in 1975 when fewer than 35 of the birds existed—has the biggest release program for cranes on Earth, and 90% of the cranes there were raised in captivity. The second viable egg from a two-egg nest was occasionally removed from the nests, starting in 1965, to become part of a captive flock. This breeding flock is divided between the Audubon Institute's Species Survival Center and White Oak Conservation in Yulee, Florida. These cranes have produced offspring for annual releases into the refuge.

A Mississippi sandhill crane was the first bird to hatch from an egg fertilized by sperm that was thawed from a cryogenic state. This occurred at the Audubon Institute, as part of this subspecies' endangered species recovery plan.

In January 2019, 25 to 30 thousand cranes (both greater and lesser subspecies) were found wintering at the Whitewater Draw State Wildlife Area near McNeal in southeast Arizona.

Sandhill cranes have been tried as foster parents for whooping cranes in reintroduction schemes. This failed when the whooping cranes imprinted on their foster parents, later did not recognize other whooping cranes as their conspecifics, and unsuccessfully tried to pair with sandhill cranes, instead.

Cuba
The Cuban sandhill crane (subspecies A. c. nesiotes) is not as rare as once believed and while it remains threatened its population is increasing. Based on very limited information, up until the 1990s it was typically believed to consist of about 300 birds. Detailed surveys conducted from 1994 to 2002 resulted in an estimate of about 525 individuals, while surveys from 2004 to 2015 estimated that the population now was above 550. Subsequent reviews have placed the Cuban sandhill crane population at around 700 birds in 2017. They inhabit dry or seasonally flooded grasslands and savannas, as well as nearby wetlands, and the remaining populations are divided into ten localities (it formerly occurred in two additional localities) in six provinces. Based on the surveys from 1994 to 2002, six of the ten known localities each are home to less than 25 Cuban sandhill cranes; the last four each are home to more than 70. The two largest, one in the Zapata Swamp (c. 120 cranes) and another on Isla de la Juventud (c.  170 cranes), are increasing, whereas most other subpopulations appear to be stable, but some likely are too small for long-term survival and possibly are decreasing. Subsequent surveys indicate that at least the four largest subpopulation now are larger than they were in the 1994–2002 surveys.

Primary threats to Cuban sandhill cranes are habitat loss due to tree planting, spreading shrubs, expanding agriculture and fires, predation by non-native mammals (dogs, mongooses and feral pigs), and poaching. Population fragmentation is also a problem, as all remaining localities are separated by distances that are greater than the largest distances non-migratory sandhill cranes are known to move.

Vagrancy
Sandhill cranes occasionally reach Europe as vagrants. The first British record was on Fair Isle in April 1981, and the second was in Shetland in 1991. Small groups have also been seen in parts of eastern China and Taiwan. In 2022, reports emerged of regular sightings of sandhill cranes in New Brunswick, on the Atlantic coast of Canada. The mythical Mothman, a humanoid creature reportedly seen in the Point Pleasant West Virginia area from November 1966 to December 1967 is thought to have originated from sightings of out-of-migration sandhill cranes.

In popular culture
In 2023 the “Mississippi sandhill crane” was featured on a United States Postal Service Forever stamp as part of the Endangered Species set, based on a photograph from Joel Sartore's Photo Ark. The stamp was dedicated at a ceremony at the National Grasslands Visitor Center in Wall, South Dakota.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/

title: Sandhill crane


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Wikipedia talk:Disambiguation and abbreviations

What is this page meant for
What is this page meant for ? The 1st para says the abbreviations are likely to be ambiguous. It also says "no need to disambiguate the abbreviations". What happens on this page ? Jay 10:24, 10 Nov 2003 (UTC)

 * Actually it reads "no need to disambiguate the abbreviations here".

 * It mainly helps you finding additional meanings for abbreviations, when you click e.g. at DC on [What links here]. Obviously, if we set up all list as state codes (which currently links both DC and District of Columbia), we wouldn't need it.

 * An advantage of keeping it out of the article namespace, is that the lists wont affect the work on Disambiguation_pages_with_links.

 * I had thought about breaking it down by sub-lists, e.g. into:
 * Undisambiguated_abbreviations/Elements
 * Undisambiguated_abbreviations/Country_codes
 * Undisambiguated_abbreviations/SI_units
 * Undisambiguated_abbreviations/CIA_World_Factbook
 * What do you think about it?
 * --User:Docu
 * --User:Docu

Today is a fresh new day, but it isn't helping me look at the page in a new light. I re-read the metapage and Docu's comments above and am still lost as ever. So here are some questions:
 * 1) "This page serves as tool to maintain them." - How are they maintained ?
 * 2) "It mainly helps you finding additional meanings for abbreviations, when you click e.g. at DC on What links here" - Why would anyone click on the 'what links here' link unless to fix incorrect redirects ? What has fixing incorrect redirects got to do with finding additional meanings ? I wasn't able to find any meanings for the 'DC' abbreviation on this page, so how is this page helping.
 * 3) "Obviously, if we set up all list as state codes (which currently links both DC and District of Columbia), we wouldn't need it." - We wouldn't need this page ? I didn't understand this line. But firstly I need to understand how this page is used.
 * 4) "...the lists wont affect the work on Wikipedia:Disambiguation pages with links" - this is a repeat of the 2nd question. How are the lists on this page related to the work on 'Wikipedia:Disambiguation pages with links' ? The latter page is generated using the assumption that any page linked from 'Wikipedia:Links to disambiguating pages' is a disambiguation page. Since 'DC' has the disambiguation statement on its page, it would ideally be made an entry in the 'Wikipedia:Disambiguation pages with links' page and dealt separately.

Jay 04:35, 11 Nov 2003 (UTC)

 * Maybe Disambiguation is a better starting point. -- User:Docu

I went through the Disambiguation page but couldn't find any topic with relevance to abbreviations except the "See also" link on the last line. What is it that you wanted me to look on the page ?

In fact I have read the page before too and have done quite a bit of disambiguation of a few pages. It seems I'm not able to see something u're able to see. So if you can answer my questions on Wikipedia_talk:Disambiguation_and_abbreviations that will sort things out. Jay 06:38, 12 Nov 2003 (UTC)

 * There isn't much of a difference between page title with ambiguous words and ambiguous abbreviations. Abbreviations are just more likely to be ambiguous.

 * If you have a set of fairly common abbreviations (e.g. List of elements by symbol), it can be helpful to make sure that the abbreviation links to the abbreviated article title (if such an article exists). You can do that with the lists included on Disambiguation_and_abbreviations. I think it's somewhat unusual to do that in article namespace (see state codes, compared to List of initialisms).

 * Disambiguation usually doesn't bother with pages outside the article namespace and is done by looking for pages linking to disambiguation pages. I'm not sure if I can help you further with your questions, maybe it's time to re-phrase Disambiguation and Disambiguation_and_abbreviations. -- User:Docu

template message for acronyms
On MediaWiki talk:Disam, I suggested a wording that could replace for two/three letter acronym pages -- User:Docu

(talk moved here) The suggest is the following:
 * For two-three letter pages, we still need a wording that is slightly different from, e.g. This page  expands and disambiguates a two or three-letter abbreviation. If you followed a link here, you might want to go back and fix that link to point to the appropriate specific page.

 * A place for the note could be MediaWiki:DisambigExpandAbbr. This allows to search for msg:disambig and find this one as well. --User:Docu

 * I don't think two and three letter acronyms are any different. It still looks like disambiguating to me if they stand for more than one thing. I don't see why the wording should be any different to distinguish the two cases. Dori | Talk 02:11, Jan 6, 2004 (UTC)

 * I agree with Dori. I can't see a reason to differentiate TLAs from other disambiguations. DisambigExpandAbbr wouldn't be a very easy to remember term if that were used. Angela. 03:23, Jan 7, 2004 (UTC)

Based on discussion elsewhere, it was better to have separate descriptions for 2LC, 3LC, and 4LC. They link to different lists, and are very easy templates to remember. These replace disambiguation pages, as they are considered encyclopedic. Most folks linking here will learn the expansion of the abbreviation, rather than clicking through to another article. (See later comments.)
 * --William Allen Simpson 14:54, 26 January 2006 (UTC)

Abbreviations, Acronyms and Wiktionary
It seems that using Wiktionary as a disambiguation resource, at least for Abbreviations and Acronyms, might be a viable alternative if a method for easy cross-referencing can be identified. Thoughts? ~ Courtland (user Ceyockey @ 16 Jan 2005)

revisiting the "one page for all cases" rule

 * Usually, there should be just one page for all cases (upper- or lower-case), e.g. MB for MB, mB, mb, Mb.

Based on Votes for deletion/SAR (which ended pretty much without a consensual conclusion), I'd like to have this statement here clarified. What does "usually" mean exactly?

In the case of SAR and Sar, the former is an acronym that expands into eleven meanings (to date), while the latter is not an acronym and it links to two words, one of which isn't exactly the same (it has diacritics stripped due to various reasons).

Should we have a poll here regarding what constitutes an exception that can apply instead of the "usual" situation described in the example? --Joy [shallot]   21:14, 21 Mar 2005 (UTC)

 * Exceptions are probably rare. SAR/sar seems like a good sample where you need just one disambiguation page (at least to me), even when there would be an article at one of the two page names (SAR/sar). In that case, a third page could have been at sar (disambiguation), but let's not exaggerate.

 * (Some of the two letter combination have not been merged yet (or have been de-merged), maybe you can find a reasonable sample there (e.g. one with more than clearly distinguishable items on each page, but it's more likely that one can tell apart a list of TLA from a list of three-letter words)). --User:Docu

 * "usually" means usually. A poll is pointless, because whether a situation is an exception depends from the individual case, the exact meanings, similarities, and distinctions of the words and the abbreviations concerned.  A case in point is LOL.  lol overlaps with LOL (Internet slang) because of the common false conflation that people make between the Dutch word and the English acronym, and because the English Internet Slang acronym is often typed in lowercase.  However lol does not overlap with "Little Old Lady" or "Loyal Orange Lodge" or any of the other expansions of the acronym which only occur in uppercase.  Therefore lol redirects directly to LOL (Internet slang), rather than being merged with LOL. Uncle G 14:13, 2005 Mar 22 (UTC)

(William M. Connolley 22:30, 3 Apr 2005 (UTC)) I'm against merging SAR and Sar, for the reasons given over there.

Where does one find Wiki abbreviations?
I was looking for help with abbreviations commonly used on Wikipedia--like dab and rv--and stumbled across this article, which isn't on that topic. Is there such a page? Thanks. --JButler 11:45, 27 August 2005 (UTC)
 * WP:ESL and/or WP:G will provide what you are looking for. It didn't take me 5 months to compose the answer, I just noticed your question. Chris the speller 17:15, 23 January 2006 (UTC)
 * Thanks just the same! --Jeremy Butler 21:23, 23 January 2006 (UTC)
 * ...and don't forget WP:WOTTA —Wahoofive (talk) 23:11, 23 January 2006 (UTC)

Lists of Abbreviations and Links to Disambiguation pages
The guidelines currently suggest that links to disambiguation pages be redirected to more appropriate targets, with which I agree. I've come around to thinking that on lists of abbreviations where both an abbreviation and an article title are linked, it is more useful for the reader to have the abbreviation link to the appropriate disambiguation page (as it is in the vast majority of cases) than redirected to the more appropriate target. For example, this would apply to the page List of IOC country codes. My reasoning is that it is useful to have a direct link to instances of potential confusion, in addition to a link to the article topic of the abbreviation thesaurus line. If this is something that seems useful to have for most people, then I would suggest addition of an exception for this to Disambiguation. I will add a link to this discussion thread to Wikipedia_talk:Disambiguation. Thanks for considering this; regards Courtland 17:03, 15 October 2005 (UTC).
 * There's no reason, IMO, to have links to anything from the three-letter codes on List of IOC country codes. Do you have other examples? If we're going to make an exception there should be a widespread need for it, not just a couple of pages. —Wahoofive (talk) 23:07, 15 October 2005 (UTC)
 * Almost every list of abbreviations has this similar issue and there are dozens of those; the IOC codes are an example only. Courtland 00:54, 16 October 2005 (UTC)

Abbreviations that are also words and disambiguation pages
I believe that the bullet point: is confusing, as it does not explain its scope when the abbreviation is also a word. For instance, should SAGE (disambiguation) necessarily be merged with Sage (disambiguation) because the former is a different casing from the latter? I think no, as "sage" is a word, while "SAGE" is an initialism. On the other hand, if a third abbreviation variant existed, say SaGE, it should go to the same place as SAGE does. I would like to change this bullet point to read something like: This would be much clearer. Again, the point of dab pages should be to get the reader to the correct article as quickly as possible, not to hew closely to formalisms. --TreyHarris 23:40, 3 January 2006 (UTC)
 * Usually, there should be just one page for all cases (upper- or lower-case), e.g. MB for MB, mB, mb, Mb.
 * Usually, there should be just one disambiguation page for all cases (upper- or lower-case), e.g. MB for MB, mB, mb, Mb. When the all-lowercase or initial-caps case(s) are words with articles in their own right, the word form should be a separate article.  Cf. Sage (disambiguation), which includes all articles disambiguating "sage" as a word,  and SAGE (disambiguation), which includes all articles disambiguating "SAGE" (and other capitalizations thereof) as an abbreviation.  In the rare case where an abbreviation is usually spelled in all-lowercase (cf. pig (disambiguation)), this abbreviation can go on both disambiguation pages.

 * Rather than "should be a separate article", how about "may be a separate article". If there are only a couple of meanings, it's easier to have them on the same page. In fact, I'd suggest the guideline should specify that this action should only be taken if there are many meanings for each version (without providing an exact number); this stems from your last point. If I type in "Spam", really looking for Spaghetti & Pulsar Activating Meatballs, I have to take an extra click just because I didn't capitalize correctly when I typed it in. —Wahoofive (talk) 03:01, 4 January 2006 (UTC)

Disambiguation terms should not be categorized or separated by criteria that the reader may not know. People, and possibly places, may be separated on the page, but capitalization, US/UK spelling, and status as abbreviation, acronym, or word may be unknown or variable. A reader looking for, say, "uncle" doesn't necessarily know whether it was the man from U.N.C.L.E., UNCLE, Uncle, or unclE he was looking for; likewise SABRE/SABER/Sabre/Saber. Are HEAT, lidar and NASA words or abbreviations? The reader may have just heard the name, or may have clicked a link which was capitalized differently, or was pipe-linked from a different term altogether. —Michael Z. 2006-01-04

 * Also see, above. —Wahoofive (talk) 03:07, 4 January 2006 (UTC)

Proposal
I think getting the reader most quickly to the right page is the consensus goal of dab pages here (though I know there are some on Wikipedia talk:Manual of Style (disambiguation pages) who disagree). I think Mzajac is right that when there's apt to be confusion, the dab page should assist them. But I also think that when the number of items on either the word or abbreviation exceeds a handful, say seven plus or minus two, that splitting them up will assist the reader more than just throwing everything on one page. (I'd like to see dab pages fit on a single screen as often as is feasible.)

So how about this (taken from the current text of the respective pages):

and

Since that text is in italics, I think it could also go at the top without disrupting the flow too much, I'm ok with either. I'd then rewrite the bullet point referenced above as a new section:

Maybe too complicated? It splits the difference, though, and accelerates getting to the right page for the largest proportion of cases. --TreyHarris 06:57, 4 January 2006 (UTC)

 * This separation into two separate pages is confusing, and just makes it harder for the reader to disambiguate; in fact may make it impossible for him to find the right link target. Two of the items in SAGE don't even have easily-determined expansions—they may be rendered in all-caps, but they are not S.A.G.E., ess-ay-gee-ee, they are sage.  Quick, why are SAGE Computer Technology and the Sage Group on two different pages?  Okay, take your time, and figure out why they are not on the same sage disambiguation page.  Say you click on a link to "sage software"—then why on Earth should the page you get to have one and not the other on it?  This is a good example of why disambiguated items should not be separated by capitalization or assumed status as abbreviations or full words.  —Michael Z. 2006-01-4 08:30 Z
 * How can it make it "impossible" to find the right target? There's a link from one to the other, and vice versa.  If they can't click a link, then they're not going to get to the right target regardless.  In any case, your zeroing in on the things with proper names of Sage and SAGE is missing the point (perhaps your example should be on both dab pages).  It seems pretty darn clear to me that the items in the top box (minus the computer company) are all of a sort, and the items in the bottom box (minus the software company) are all of a sort, and they're not of the same sort.

 * My point here is to try to reduce cognitive load. The items under the word "sage" and the items under the acronym "SAGE" are each of a sort.  If we were to order a merged page by the MOS:DP, we would have:

 * Do you really find that easier to navigate than the two pages above? For me at least, the cognitive load of that list makes my head spin.  Sorting into sections doesn't help in this case, as the items are too scattershot (at best, we could create a "companies" section that contained two items).  I suspect one of the first sectionals that someone would create is "SAGE as an abbreviation", and then we're back where we started. --TreyHarris 09:12, 4 January 2006 (UTC)
 * While I don't feel that strongly about this either way, your last example is sort of a straw man. There's no reason you couldn't create separate sections on the page for different types of usage; in fact the WP:MOSDAB explicitly encourages this when there are lots of links. —Wahoofive (talk) 22:56, 4 January 2006 (UTC)
 * I mentioned that, but what sections would you use? Each item above (except for The Sage Group and SAGE Computer Technology, which are both companies) are different types of things.  One section for each link?  What good does that do over having two pages, besides just spacing things out a bit? Maybe I'm missing the point; why don't you show me what a well-organized, MoS-following, easily-navigable merged dab page would look like? --TreyHarris 23:18, 4 January 2006 (UTC)
 * Response to section proposal called Abbreviations and words spelled alike: Good, but too long. How about just the first paragraph? Everything else is subsumed under use common sense. And I still vote for "may" rather than "should". —Wahoofive (talk) 23:14, 4 January 2006 (UTC)
 * How's this?

 * —Wahoofive (talk) 23:30, 4 January 2006 (UTC)

 * I like this one - the subheads make it easier to read even though it dumps a common meaning at the bottom. JackyR 01:11, 19 January 2006 (UTC)

I'd keep the descriptions just complex enough to distinguish, and put the most basic meanings first: —Michael Z. 2006-01-4 23:34 Z

Sage may refer to:
 * Sage, a Wise Old Man
 * Sage, an herb
 * Sage (comics), a superhero
 * Sage (Mozilla Firefox extension), Internet news feed reader
 * SAGE (organization), IT workers' professional body
 * SAGE Computer Technology, formerly Stride Computers
 * Sage Francis, rap musician
 * Sage Gateshead, an English music centre
 * The Sage Group software company
 * Rishi, in Hindu myth
 * Sativa Afghani Genetic Equilibrium (SAGE), a strain of cannabis
 * Semi Automatic Ground Environment (SAGE), a NORAD computer system
 * Serial Analysis of Gene Expression (SAGE)

Resolution
I have merged SAGE (disambiguation) into Sage (disambiguation), following Wahoofive's model. --TreyHarris 04:08, 19 January 2006 (UTC)
 * You done good. You BOTH done good. Chris the speller 17:35, 23 January 2006 (UTC)

Yes, that was a good thing to do, but shouldn't it have been at SAGE? I've been following the literal convention on the page (that is, "MB"), and found that most existing redirects from the two and three letter combination pages are from mixed to all upper. Was this chosen because the Primary topic is "Sage"? (That seems to be reasonable, but wasn't spelled out here, and should have a Primary in that case.)
 * --William Allen Simpson 15:25, 26 January 2006 (UTC)

 * The guidelines specify listing a primary topic (i.e., the primary topic when one exists) in a sentence as the first line of text. Primary is inconsistent with this, and should not be used on Dab pages. Expect to see it on TfD this week. --Jerzy•t 19:53, 23 February 2009 (UTC)

Consensus of one
Mr William Allen Simpson is trying to sneak in a new policy instituting "abbreviation expansion" pages. Please express your opinion for or against the idea at Wikipedia talk:Abbreviation expansion. —Michael Z. 2006-04-02 04:36 Z

Are disambig pages part of the encyclopaedia?
Is there any consensus over whether disambig pages are themselves supposed to be encyclopaedic, or are they simply a practical tool for encyclopaedia readers? In particular, should a TLA disambig page reference all possible interpretations of that abbreviation (as would be encyclopaedic), or only those that a reader would likely search under (as would fit the latter interpretation)? Should redlinks ever be included in a disambig page? How much other information should be included on it? Stevage 12:34, 31 May 2006 (UTC)

Standardisation of names of two-letter combination pages
Currently, about 90% of the various 2LC dab pages use upper case for both letters; the remaining 10% use upper then lower. I'd like to see this standardised to both upper and have commented to such effect at Wikipedia talk:Naming conventions. Please comment there if you wish to voice an opinion! Grutness...wha?  12:16, 12 December 2006 (UTC)

abbreviations should usually be expanded beforehand ??
From intro: "abbreviations should usually be expanded [...] beforehand". Beforehand? Before what? Nurg 22:29, 5 October 2007 (UTC)

"Abbreviations pages replace disambiguation pages" ??
"Abbreviations pages replace disambiguation pages". What does this mean? Does it mean there should not be disambiguation pages for acronyms or abbreviations, but rather that acronyms and abbreviations should be disambiguated by "abbreviations pages", whatever these are? Nurg 22:53, 5 October 2007 (UTC)
 * I also found this odd. Abbreviations pages are a type of disambiguation page. -- JHunterJ 23:32, 5 October 2007 (UTC)
 * I find this whole page odd. I just clicked a link here, read it through, and have absolutely no idea what it's about. (Well if I concentrated hard enough I might be able to guess pieces of it.) If there is wisdom concealed here, there needs to be a major rewrite in order to bring it to the surface.--Kotniski (talk) 15:39, 11 August 2008 (UTC)

Proposed demotion
Proposing merging this page (or at least, the information on it that makes any sense) with Disambiguation. Most of the information is there already anyway.--Kotniski (talk) 11:06, 21 August 2008 (UTC)

 * Actually, I propose removing guideline status from this page, and then either deleting it or retaining it as a historical page. All the guidance here (if any of it is meaningful) is duplicated or superseded at WP:D and WP:MOSDAB; the only potential added value is the list of lists of abbreviations, but that hardly justifies maintaining the page as a guideline.--Kotniski (talk) 19:42, 22 August 2008 (UTC)
 * I siupport removal and deletion/archiving. Tony   (talk)  05:49, 25 August 2008 (UTC)
 * ✅ changed to "historical"--Kotniski (talk) 07:43, 25 August 2008 (UTC)

TLA
Shouldn't WP:TLA point to the same page as WP:WOTTA, rather than here? / habj (talk) 21:45, 16 November 2008 (UTC)


text:
Terahertz radiation

Terahertz radiation – also known as submillimeter radiation, terahertz waves, tremendously high frequency (THF), T-rays, T-waves, T-light, T-lux or THz – consists of electromagnetic waves within the ITU-designated band of frequencies from 0.3 to 3 terahertz (THz), although the upper boundary is somewhat arbitrary and is considered by some sources as 30 THz. One terahertz is 1012 Hz or 1,000 GHz. Wavelengths of radiation in the terahertz band correspondingly range from 1 mm to 0.1 mm = 100 μm. Because terahertz radiation begins at a wavelength of around 1 millimeter and proceeds into shorter wavelengths, it is sometimes known as the submillimeter band, and its radiation as submillimeter waves, especially in astronomy. This band of electromagnetic radiation lies within the transition region between microwave and far infrared, and can be regarded as either.

Compared to lower radio frequencies, terahertz radiation is strongly absorbed by the gases of the atmosphere, and in air most of the energy is attenuated within a few meters,  so it is not practical for long distance terrestrial radio communication. It can penetrate thin layers of materials but is blocked by thicker objects. THz beams transmitted through materials can be used for material characterization, layer inspection, relief measurement, and as a lower-energy alternative to X-rays for producing high resolution images of the interior of solid objects.

Terahertz radiation occupies a middle ground where the ranges of microwaves and infrared light waves overlap, known as the "terahertz gap"; it is called a "gap" because the technology for its generation and manipulation is still in its infancy. The generation and modulation of electromagnetic waves in this frequency range ceases to be possible by the conventional electronic devices used to generate radio waves and microwaves, requiring the development of new devices and techniques.

Description

Terahertz radiation falls in between infrared radiation and microwave radiation in the electromagnetic spectrum, and it shares some properties with each of these. Terahertz radiation travels in a line of sight and is non-ionizing. Like microwaves, terahertz radiation can penetrate a wide variety of non-conducting materials; clothing, paper, cardboard, wood, masonry, plastic and ceramics. The penetration depth is typically less than that of microwave radiation. Like infrared, terahertz radiation has limited penetration through fog and clouds and cannot penetrate liquid water or metal. Terahertz radiation can penetrate some distance through body tissue like x-rays, but unlike them is non-ionizing, so it is of interest as a replacement for medical X-rays. Due to its longer wavelength, images made using terahertz waves have lower resolution than X-rays and need to be enhanced (see figure at right).

The earth's atmosphere is a strong absorber of terahertz radiation, so the range of terahertz radiation in air is limited to tens of meters, making it unsuitable for long-distance communications. However, at distances of ~10 meters the band may still allow many useful applications in imaging and construction of high bandwidth wireless networking systems, especially indoor systems. In addition, producing and detecting coherent terahertz radiation remains technically challenging, though inexpensive commercial sources now exist in the 0.3–1.0 THz range (the lower part of the spectrum), including gyrotrons, backward wave oscillators, and resonant-tunneling diodes. Due to the small energy of THz photons, current THz devices require low temperature during operation to suppress environmental noise. Tremendous efforts thus have been put into THz research to improve the operation temperature, using different strategies such as optomechanical meta-devices.

Natural
Terahertz radiation is emitted as part of the black-body radiation from anything with a temperature greater than about 2 kelvins. While this thermal emission is very weak, observations at these frequencies are important for characterizing cold 10–20 K cosmic dust in interstellar clouds in the Milky Way galaxy, and in distant starburst galaxies.

Telescopes operating in this band include the James Clerk Maxwell Telescope, the Caltech Submillimeter Observatory and the Submillimeter Array at the Mauna Kea Observatory in Hawaii, the BLAST balloon borne telescope, the Herschel Space Observatory, the Heinrich Hertz Submillimeter Telescope at the Mount Graham International Observatory in Arizona, and at the recently built Atacama Large Millimeter Array. Due to Earth's atmospheric absorption spectrum, the opacity of the atmosphere to submillimeter radiation restricts these observatories to very high altitude sites, or to space.

Artificial
, viable sources of terahertz radiation are the gyrotron, the backward wave oscillator ("BWO"), the organic gas far infrared laser, Schottky diode multipliers, varactor (varicap) multipliers, quantum cascade laser,   the free electron laser, synchrotron light sources, photomixing sources, single-cycle or pulsed sources used in terahertz time domain spectroscopy such as photoconductive, surface field, photo-Dember and optical rectification emitters, and electronic oscillators based on resonant tunneling diodes have been shown to operate up to 1.98 THz.

There have also been solid-state sources of millimeter and submillimeter waves for many years. AB Millimeter in Paris, for instance, produces a system that covers the entire range from 8 GHz to 1,000 GHz with solid state sources and detectors. Nowadays, most time-domain work is done via ultrafast lasers.

In mid-2007, scientists at the U.S. Department of Energy's Argonne National Laboratory, along with collaborators in Turkey and Japan, announced the creation of a compact device that could lead to portable, battery-operated terahertz radiation sources. The device uses high-temperature superconducting crystals, grown at the University of Tsukuba in Japan. These crystals comprise stacks of Josephson junctions, which exhibit a property known as the Josephson effect: when external voltage is applied, alternating current flows across the junctions at a frequency proportional to the voltage. This alternating current induces an electromagnetic field. A small voltage (around two millivolts per junction) can induce frequencies in the terahertz range.

In 2008, engineers at Harvard University achieved room temperature emission of several hundred nanowatts of coherent terahertz radiation using a semiconductor source. THz radiation was generated by nonlinear mixing of two modes in a mid-infrared quantum cascade laser. Previous sources had required cryogenic cooling, which greatly limited their use in everyday applications.

In 2009, it was discovered that the act of unpeeling adhesive tape generates non-polarized terahertz radiation, with a narrow peak at 2 THz and a broader peak at 18 THz. The mechanism of its creation is tribocharging of the adhesive tape and subsequent discharge; this was hypothesized to involve bremsstrahlung with absorption or energy density focusing during dielectric breakdown of a gas.

In 2013, researchers at Georgia Institute of Technology's Broadband Wireless Networking Laboratory and the Polytechnic University of Catalonia developed a method to create a graphene antenna: an antenna that would be shaped into graphene strips from 10 to 100 nanometers wide and one micrometer long. Such an antenna could be used to emit radio waves in the terahertz frequency range.

Terahertz gap
In engineering, the terahertz gap is a frequency band in the THz region for which practical technologies for generating and detecting the radiation do not exist. It is defined as 0.1 to 10 THz (wavelengths of 3 mm to 30 μm) although the upper boundary is somewhat arbitrary and is considered by some sources as 30 THz (a wavelength of 10 μm). Currently, at frequencies within this range, useful power generation and receiver technologies are inefficient and unfeasible.

Mass production of devices in this range and operation at room temperature (at which energy kT is equal to the energy of a photon with a frequency of 6.2 THz) are mostly impractical. This leaves a gap between mature microwave technologies in the highest frequencies of the radio spectrum and the well-developed optical engineering of infrared detectors in their lowest frequencies. This radiation is mostly used in small-scale, specialized applications such as submillimetre astronomy. Research that attempts to resolve this issue has been conducted since the late 20th century.

In 2024, an experiment has been published by german researchers where a TDLAS experiment at 4.75 THz has been performed in "infrared quality" with an uncooled pyroelectric receiver while the THz source has been a cw DFB-QC-Laser operated at 43.3 K and laser currents between 480 mA and 600 mA.

Closure of the terahertz gap
Most vacuum electronic devices that are used for microwave generation can be modified to operate at terahertz frequencies, including the magnetron, gyrotron, synchrotron, and free electron laser. Similarly, microwave detectors such as the tunnel diode have been re-engineered to detect at terahertz and infrared frequencies as well. However, many of these devices are in prototype form, are not compact, or exist at university or government research labs, without the benefit of cost savings due to mass production.

Medical imaging
Unlike X-rays, terahertz radiation is not ionizing radiation and its low photon energies in general do not damage living tissues and DNA. Some frequencies of terahertz radiation can penetrate several millimeters of tissue with low water content (e.g., fatty tissue) and reflect back. Terahertz radiation can also detect differences in water content and density of a tissue. Such methods could allow effective detection of epithelial cancer with an imaging system that is safe, non-invasive, and painless. In response to the demand for COVID-19 screening terahertz spectroscopy and imaging has been proposed as a rapid screening tool.

The first images generated using terahertz radiation date from the 1960s; however, in 1995 images generated using terahertz time-domain spectroscopy generated a great deal of interest.

Some frequencies of terahertz radiation can be used for 3D imaging of teeth and may be more accurate than conventional X-ray imaging in dentistry.

Security
Terahertz radiation can penetrate fabrics and plastics, so it can be used in surveillance, such as security screening, to uncover concealed weapons on a person, remotely. This is of particular interest because many materials of interest have unique spectral "fingerprints" in the terahertz range. This offers the possibility to combine spectral identification with imaging. In 2002, the European Space Agency (ESA) Star Tiger team, based at the Rutherford Appleton Laboratory (Oxfordshire, UK), produced the first passive terahertz image of a hand. By 2004, ThruVision Ltd, a spin-out from the Council for the Central Laboratory of the Research Councils (CCLRC) Rutherford Appleton Laboratory, had demonstrated the world's first compact THz camera for security screening applications. The prototype system successfully imaged guns and explosives concealed under clothing. Passive detection of terahertz signatures avoid the bodily privacy concerns of other detection by being targeted to a very specific range of materials and objects.

In January 2013, the NYPD announced plans to experiment with the new technology to detect concealed weapons, prompting Miami blogger and privacy activist Jonathan Corbett to file a lawsuit against the department in Manhattan federal court that same month, challenging such use: "For thousands of years, humans have used clothing to protect their modesty and have quite reasonably held the expectation of privacy for anything inside of their clothing, since no human is able to see through them." He sought a court order to prohibit using the technology without reasonable suspicion or probable cause. By early 2017, the department said it had no intention of ever using the sensors given to them by the federal government.

Scientific use and imaging
In addition to its current use in submillimetre astronomy, terahertz radiation spectroscopy could provide new sources of information for chemistry and biochemistry.

Recently developed methods of THz time-domain spectroscopy (THz TDS) and THz tomography have been shown to be able to image samples that are opaque in the visible and near-infrared regions of the spectrum. The utility of THz-TDS is limited when the sample is very thin, or has a low absorbance, since it is very difficult to distinguish changes in the THz pulse caused by the sample from those caused by long-term fluctuations in the driving laser source or experiment. However, THz-TDS produces radiation that is both coherent and spectrally broad, so such images can contain far more information than a conventional image formed with a single-frequency source.

Submillimeter waves are used in physics to study materials in high magnetic fields, since at high fields (over about 11 tesla), the electron spin Larmor frequencies are in the submillimeter band. Many high-magnetic field laboratories perform these high-frequency EPR experiments, such as the National High Magnetic Field Laboratory (NHMFL) in Florida.

Terahertz radiation could let art historians see murals hidden beneath coats of plaster or paint in centuries-old buildings, without harming the artwork.

In additional, THz imaging has been done with lens antennas to capture radio image of the object.

Particle accelerators
New types of particle accelerators that could achieve multi Giga-electron volts per metre (GeV/m) accelerating gradients are of utmost importance to reduce the size and cost of future generations of high energy colliders as well as provide a widespread availability of compact accelerator technology to smaller laboratories around the world. Gradients in the order of 100 MeV/m have been achieved by conventional techniques and are limited by RF-induced plasma breakdown. Beam driven dielectric wakefield accelerators (DWAs) typically operate in the Terahertz frequency range, which pushes the plasma breakdown threshold for surface electric fields into the multi-GV/m range. DWA technique allows to accommodate a significant amount of charge per bunch, and gives an access to conventional fabrication techniques for the accelerating structures. To date 0.3 GeV/m accelerating and 1.3 GeV/m decelerating gradients have been achieved using a dielectric lined waveguide with sub-millimetre transverse aperture.

An accelerating gradient larger than 1 GeV/m, can potentially be produced by the Cherenkov Smith-Purcell radiative mechanism in a dielectric capillary with a variable inner radius. When an electron bunch propagates through the capillary, its self-field interacts with the dielectric material and produces wakefields that propagate inside the material at the Cherenkov angle. The wakefields are slowed down below the speed of light, as the relative dielectric permittivity of the material is larger than 1. The radiation is then reflected from the capillary's metallic boundary and diffracted back into the vacuum region, producing high accelerating fields on the capillary axis with a distinct frequency signature. In presence of a periodic boundary the Smith-Purcell radiation imposes frequency dispersion.

A preliminary study with corrugated capillaries has shown some modification to the spectral content and amplitude of the generated wakefields, but the possibility of using Smith-Purcell effect in DWA is still under consideration.

Communication
The high atmospheric absorption of terahertz waves limits the range of communication using existing transmitters and antennas to tens of meters. However, the huge unallocated bandwidth available in the band (ten times the bandwidth of the millimeter wave band, 100 times that of the SHF microwave band) makes it very attractive for future data transmission and networking use. There are tremendous difficulties to extending the range of THz communication through the atmosphere, but the world telecommunications industry is funding much research into overcoming those limitations. One promising application area is the 6G cellphone and wireless standard, which will supersede the current 5G standard around 2030.

For a given antenna aperture, the gain of directive antennas scales with the square of frequency, while for low power transmitters the power efficiency is independent of bandwidth. So the consumption factor theory of communication links indicates that, contrary to conventional engineering wisdom, for a fixed aperture it is more efficient in bits per second per watt to use higher frequencies in the millimeter wave and terahertz range. Small directive antennas a few centimeters in diameter can produce very narrow 'pencil' beams of THz radiation, and phased arrays of multiple antennas could concentrate virtually all the power output on the receiving antenna, allowing communication at longer distances.

In May 2012, a team of researchers from the Tokyo Institute of Technology published in Electronics Letters that it had set a new record for wireless data transmission by using T-rays and proposed they be used as bandwidth for data transmission in the future. The team's proof of concept device used a resonant tunneling diode (RTD) negative resistance oscillator to produce waves in the terahertz band. With this RTD, the researchers sent a signal at 542 GHz, resulting in a data transfer rate of 3 Gigabits per second. It doubled the record for data transmission rate set the previous November. The study suggested that Wi-Fi using the system would be limited to approximately 10 m, but could allow data transmission at up to 100 Gbit/s. In 2011, Japanese electronic parts maker Rohm and a research team at Osaka University produced a chip capable of transmitting 1.5 Gbit/s using terahertz radiation.

Potential uses exist in high-altitude telecommunications, above altitudes where water vapor causes signal absorption: aircraft to satellite, or satellite to satellite.

Amateur radio
A number of administrations permit amateur radio experimentation within the 275–3,000 GHz range or at even higher frequencies on a national basis, under license conditions that are usually based on RR5.565 of the ITU Radio Regulations. Amateur radio operators utilizing submillimeter frequencies often attempt to set two-way communication distance records. In the United States, WA1ZMS and W4WWQ set a record of 1.42 km on 403 GHz using CW (Morse code) on 21 December 2004. In Australia, at 30 THz a distance of 60 m was achieved by stations VK3CV and VK3LN on 8 November 2020.

Manufacturing
Many possible uses of terahertz sensing and imaging are proposed in manufacturing, quality control, and process monitoring. These in general exploit the traits of plastics and cardboard being transparent to terahertz radiation, making it possible to inspect packaged goods. The first imaging system based on optoelectronic terahertz time-domain spectroscopy were developed in 1995 by researchers from AT&T Bell Laboratories and was used for producing a transmission image of a packaged electronic chip. This system used pulsed laser beams with duration in range of picoseconds. Since then commonly used commercial/ research terahertz imaging systems have used pulsed lasers to generate terahertz images. The image can be developed based on either the attenuation or phase delay of the transmitted terahertz pulse.

Since the beam is scattered more at the edges and also different materials have different absorption coefficients, the images based on attenuation indicates edges and different materials inside of objects. This approach is similar to X-ray transmission imaging, where images are developed based on attenuation of the transmitted beam.

In the second approach, terahertz images are developed based on the time delay of the received pulse. In this approach, thicker parts of the objects are well recognized as the thicker parts cause more time delay of the pulse. Energy of the laser spots are distributed by a Gaussian function. The geometry and behavior of Gaussian beam in the Fraunhofer region imply that the electromagnetic beams diverge more as the frequencies of the beams decrease and thus the resolution decreases. This implies that terahertz imaging systems have higher resolution than scanning acoustic microscope (SAM) but lower resolution than X-ray imaging systems. Although terahertz can be used for inspection of packaged objects, it suffers from low resolution for fine inspections. X-ray image and terahertz images of an electronic chip are brought in the figure on the right. Obviously the resolution of X-ray is higher than terahertz image, but X-ray is ionizing and can be impose harmful effects on certain objects such as semiconductors and live tissues.

To overcome low resolution of the terahertz systems near-field terahertz imaging systems are under development. In nearfield imaging the detector needs to be located very close to the surface of the plane and thus imaging of the thick packaged objects may not be feasible. In another attempt to increase the resolution, laser beams with frequencies higher than terahertz are used to excite the p-n junctions in semiconductor objects, the excited junctions generate terahertz radiation as a result as long as their contacts are unbroken and in this way damaged devices can be detected. In this approach, since the absorption increases exponentially with the frequency, again inspection of the thick packaged semiconductors may not be doable. Consequently, a tradeoff between the achievable resolution and the thickness of the penetration of the beam in the packaging material should be considered.

THz gap research
Ongoing investigation has resulted in improved emitters (sources) and detectors, and research in this area has intensified. However, drawbacks remain that include the substantial size of emitters, incompatible frequency ranges, and undesirable operating temperatures, as well as component, device, and detector requirements that are somewhere between solid state electronics and photonic technologies.

Free-electron lasers can generate a wide range of stimulated emission of electromagnetic radiation from microwaves, through terahertz radiation to X-ray. However, they are bulky, expensive and not suitable for applications that require critical timing (such as wireless communications). Other sources of terahertz radiation which are actively being researched include solid state oscillators (through frequency multiplication), backward wave oscillators (BWOs), quantum cascade lasers, and gyrotrons.

Safety
The terahertz region is between the radio frequency region and the laser optical region. Both the IEEE C95.1–2005 RF safety standard and the ANSI Z136.1–2007 Laser safety standard have limits into the terahertz region, but both safety limits are based on extrapolation. It is expected that effects on biological tissues are thermal in nature and, therefore, predictable by conventional thermal models. Research is underway to collect data to populate this region of the spectrum and validate safety limits.

A theoretical study published in 2010 and conducted by Alexandrov et al at the Center for Nonlinear Studies at Los Alamos National Laboratory in New Mexico created mathematical models predicting how terahertz radiation would interact with double-stranded DNA, showing that, even though involved forces seem to be tiny, nonlinear resonances (although much less likely to form than less-powerful common resonances) could allow terahertz waves to "unzip double-stranded DNA, creating bubbles in the double strand that could significantly interfere with processes such as gene expression and DNA replication". Experimental verification of this simulation was not done. Swanson's 2010 theoretical treatment of the Alexandrov study concludes that the DNA bubbles do not occur under reasonable physical assumptions or if the effects of temperature are taken into account. A bibliographical study published in 2003 reported that T-ray intensity drops to less than 1% in the first 500 μm of skin but stressed that "there is currently very little information about the optical properties of human tissue at terahertz frequencies".

title: Terahertz radiation


text:
Craft beer

Craft beer is a beer that has been made by craft breweries, which typically produce smaller amounts of beer, than larger "macro" breweries, and are often independently owned. Such breweries are generally perceived and marketed as emphasising enthusiasm, new flavours, and varied brewing techniques.

The microbrewery movement began in both the United States and United Kingdom in the 1970s, although traditional artisanal brewing existed in Europe for centuries and subsequently spread to other countries. As the movement grew, and some breweries expanded their production and distribution, the more encompassing concept of craft brewing emerged. A brewpub is a pub that brews its own beer for sale on the premises.

Microbrewery
Although the term "microbrewery" was originally used in relation to the size of breweries, it gradually came to reflect an alternative attitude and approach to brewing flexibility, adaptability, experimentation and customer service. The term and trend spread from the UK to the US in the 1980s, and was eventually used as a designation for breweries that produce fewer than 15000 USbeerbbl annually. In 1995, there were 205 microbreweries nationwide. In 2000, that number more than doubled to 420 microbreweries.

Nanobrewery
The website The Food Section defines a "nanobrewery" as, "a scaled-down microbrewery, often run by a solo entrepreneur, that produces beer in small batches." Nanobrewers often work out of garages or small industrial spaces. Small batches are then sold to local bars or directly to customers. The U.S. Department of the Treasury defines nanobreweries as "very small brewery operations" that produce beer for sale. These small operations still must meet state and federal licensing requirements. In 2013, there were more than 200 "nanos" in the United States. With lower startup costs than a craft brewery, nanobreweries have become popular among home brewers looking to expand and practice their beer brewing skills.

Craft brewery
"Craft brewing" is a more encompassing term for developments in the industry succeeding the microbrewing movement of the late 20th century. The definition is not entirely consistent but typically applies to relatively small, independently owned commercial breweries that employ traditional brewing methods and emphasize flavor and quality. The term is usually reserved for breweries established since the 1970s but may be used for older breweries with a similar focus. A United States trade group, the Brewers Association, interested in brand transparency, offers a definition of craft breweries as "small, independent and traditional". The craft brewing process takes time and can be considered an art by the brewmasters. In the United Kingdom, the Assured Independent British Craft Brewer initiative is run by the Society of Independent Brewers (SIBA), who ensure that any breweries using the Independent Craft Brewer logo are relatively small, independent and brewing quality beer.

Farm brewery
The term "farm brewery" or "farmhouse brewery" has been around for centuries. Several beer styles are considered "farmhouse," originally stemming from farmers brewing low ABV beer as an incentive for field workers. Farm breweries were not large scale; they had smaller, more unique, methods of brewing and fermenting in comparison to the larger breweries of the time. This had different effects on the overall product, creating unconventional beer flavors.

The term "farm brewery" has more recently found its way into several local and state laws in order to give farm breweries certain, often agriculturally related, privileges not normally found under standard brewery laws. These privileges usually come at a price: some portion of the ingredients (such as grains, hops, or fruit) used in the beer must be grown on the given licensed farm brewery.

Brewpub
Brewpub is an abbreviated term combining the ideas of a brewery and a pub or public-house. A brewpub can be a pub or restaurant that brews beer on the premises. In the United States a brewpub is defined as selling 25 percent or more of its beer on-site and operating significant food services. A taproom brewery is a professional brewery that sells 25 percent or more of its beer on-site and does not operate significant food services. The beer is brewed primarily for sale in the taproom, and is often dispensed directly from the brewery's storage tanks.

In the European Union, brewpubs in some countries are favoured by a system of progressive beer duty, which originated in Bavaria. In the United Kingdom brewpubs brewing up to 5,000 hectolitres a year (about 880,000 pints) pay just half of ordinary beer duty rates.

Marketing strategy
Craft beer has adopted a marketing strategy that differs from those of the large, mass-market breweries, offering products that compete on the basis of quality and diversity instead of low price and advertising. Their influence has been much greater than their market share, which amounts to only 2% in the UK, indicated by the introduction by large commercial breweries of new brands for the craft beer market. However, when the strategy failed, the corporate breweries invested in microbreweries or, in many cases, acquired them outright.

Canned beer
The American Can Company developed the first beer can in 1933 after years of researching how to create a can that would hold a pressurized carbonated beverage. They also created a special coating on the inside of a can to prevent a metallic taste from affecting the beer. The first can of beer was sold on January 24, 1935, when the American Can Company partnered with New Jersey-based Gottfried Krueger Brewing Company, delivering two thousand cans of Krueger's Finest Beer and Krueger's Cream Ale to people in Richmond, Virginia. By the end of the year, 37 breweries were canning their beer.

In the United Kingdom, the Felinfoel Brewery sold the first canned beer in Europe in January 1936.

In 1962, a brewing company in Pittsburg introduced the first self-opening can, which later became a pull ring tab, eliminating the need for a separate opening device.

The use of cans by craft brewers doubled between 2012 and 2014, with over 500 companies in the United States using cans to package their beverages. Previously associated with the major brewing corporations, cans are now favored by craft brewers for numerous reasons: cans are impervious to oxygen, beer-degrading light does not affect canned beer, canned beer is more portable since less room is required for storage or transportation, canned beer cools more quickly, and cans have a greater surface area for wraparound designs and decorations.

The perception that bottles lead to a taste that is superior to canned beer has been called "just kind of dated," as most aluminum cans are lined with a polymer coating that protects the beer from the problematic metal. However, since drinking directly from a can may still result in a metallic taste, most craft brewers recommend pouring beer into a glass prior to consumption. In June 2014, the BA estimated 3% of craft beer is sold in cans, 60% is sold in bottles, and kegs represent the remainder of the market.

Between 2015 and 2020, the proportion of craft beer packaged in cans in the UK increased nearly tenfold to 4.9 percent.

Barrel-aged beer

Goose Island first produced its Bourbon County Stout in 1992, but it was not regularly available until 2005. Other breweries began following Goose Island's lead, typically aging rich imperial stouts such as Founders KBS and The Bruery's Black Tuesday. In 2018, Food and Drink wrote: "A process that was once niche has become not just mainstream, but ubiquitous." Barrel-aged sour beers are a newer trend, inspired by the Belgian tradition of lambics and Flanders red ale.

Non-alcoholic craft beers
The market for non-alcoholic beer and wine in North America is predicted to quadruple from a base of about $20 million in 2018. Brooklyn Brewery are among the early craft breweries prepared to release a non-alcoholic craft beer, with their "Special Effects." Examples in Europe include Mikkeller's "Drink'in The Sun" and Nirvana's gluten-free "Kosmic Stout".

Cambodia
Cambodia's first microbrewery, Kingdom Breweries, opened in 2009 and brews dark, pilsener, and lager beers.

China

China, the world's largest beer consumer as of July 2013, is home to a growing craft beer market, with brands such as Slowboat Brewery, Jing-A Brewery, and Boxing Cat Brewery. By July 2013, the number of brewpubs in Shanghai, China had doubled since 2010. General beer consumption reached 50 e6L in early 2013 and an increasing interest in craft beers developed accordingly. The Great Leap Brewing Company is one example of numerous microbreweries that have been recently established, with a localization strategy leading to the use of traditional Chinese ingredients and spices in the Beijing brand's beer production process. China's largest brewpub is located in Suzhou and is managed by the Taiwanese brewing company Le Ble D'or, while craft beer consumers are both ex-pats and native Chinese.

India
India's first microbrewery, Doolally, was opened in Pune in 2009. In 2019, Bangalore had over 60 microbreweries.

Japan
An early boom in small regional microbreweries followed Japan's 1994 revision of tax laws allowing the establishment of smaller breweries producing 60000 L per year. Before this change, breweries could not get a license without producing at least 2000000 L per year. Beer produced by microbreweries in the early 1990s was commonly referred to as Ji Bīru (地ビール), or "local beer." In the late 2000s, more established microbreweries in Japan chose to emphasize the term Craft Beer (クラフトビア) to mark a break with the short-lived Ji Bīru boom and to emphasize the traditional brewing skills and reverence for ingredients that characterize their products.

Sri Lanka
In Sri Lanka, over-strict laws made it almost impossible for any craft beer to be brewed. On the remote East Coast, however, "Arugam Bay Surfer's Beer" managed to maintain a small, but popular brewpub. Established in 1977, the Siam View Hotel escaped regulations due to the long civil war and its remoteness. For two years running, the Daily Telegraph "Best of British" awarded the Siam View Hotel the "Best Pub in Sri Lanka" medal.

Taiwan
In Taiwan, where a single beer company dominates the market, the craft beer market has grown with brewers such as Redpoint Brewing Company gaining increasing market exposure through local bars and restaurants. This market trend has been accompanied by craft beer festivals where expat and Taiwanese brewers showcase their beer.

Thailand
Following the introduction of American microbrews in 2012, the popularity of craft beer bars in Thailand—primarily Bangkok—increased fairly rapidly and in January 2014, the fourth global location of Danish microbrewery Mikkeller was launched in Bangkok. The brand partnered with an already established beer distribution company and seeks to capitalize on the higher earning capacity of Thai people in the second decade of the 21st century, as well as tourists. At the opening, one of the owners explained: "... and we thought it was about time to elevate the level of craft beer available in Thailand and, hopefully, expand throughout Southeast Asia." A total of 30 beers are served at the venue, including two microbrews exclusive to Thailand.

Vietnam
Vietnam is the largest producer of craft beer in Southeast Asia, with microbreweries producing 31,000 hectolitres in 2018.

With a beer culture that emerged during French colonisation and further influenced by Vietnamese students returning from overseas studies,, there were 31 microbreweries in Vietnam. Established microbreweries include Heart of Darkness Craft Brewery, BiaCraft, Platinum Beers, Fuzzy Logic and Pasteur Street Brewing Company.

Czech Republic
There has been a boom of craft beer breweries. Despite strong tradition of drinking Czech beer there is a growing craft beer scene in the Czech Republic focused on non-traditional beer styles. Notable breweries include Matuška, Clock and Zichovec. What makes Czech craft beer unique is the common use of decoction instead of just infusion even for top fermented beers.

Denmark
In Denmark microbreweries have occurred throughout the country in increasing numbers. Small microbreweries often relate to restaurants and pubs, but local microbrewed craft beers are also sold in stores.

Estonia
Estonia has a tradition of home-brewed farm beers which are often flavoured with juniper. Craft beer came late to Estonia, but that began to change in 2012 when Mikkeller brewed a custom beer for the Estonian market, called Baltic Frontier. Then one local brewer in particular, Põhjala, led the way for other Estonian microbrewers such as Lehe, Koeru and Õllenaut. By 2017 there were nearly 30 microbreweries on the Estonian market, in a country with a population of only 1.2 million. Since 2015 Põhjala Brewery has organised an annual craft beer festival called "Tallinn Craft Beer Weekend".

Finland
The legislation in Finland allows craft breweries to sell their products directly to consumers.

France
France may be more commonly associated with wine, but its craft beer scene is also popular, ranging from classic farmhouse ales to experimental styles infused with local ingredients like lavender or foie gras.

Today, there are hundreds of craft breweries across France. Many draw inspiration from traditional European styles like Belgian saisons and German pilsners, while others experiment with unique ingredients like chestnuts or wildflowers.

Germany
Some microbreweries, such as those in Germany, have been brewing traditionally for hundreds of years. In Germany, there were 901 small breweries in 2010. The Federal Statistical Office defines a small brewery as a brewery with a production of less than 5,000 hectoliters (132,086 US gallons) beer p.a. Small breweries pay a reduced beer tax.

The total market share of the small breweries is less than 1%. 638 of them have a production even less than 1,000 hl (26,417.2 US gal.) p.a. and can be considered as microbreweries in a narrow sense. The figures apply to commercial breweries only and do not include hobby brewing.

About one third of the small breweries have a tradition going back up to 500 years, most of them in Franconia. About two thirds were founded in the last 25 years. The vast majority of small breweries operate in combination with a brewpub.

Whereas in other countries, microbreweries and brewpubs have risen in reaction to the mass production and marketing of beer, in Germany, the traditional brewpub or Brauhaus remains a major source of beer. This is mainly true for the South of Germany, especially the state of Bavaria. Upper Franconia, a district in the Region Franconia in the north of Bavaria, has the highest density of breweries in the world. Upper Franconia has about one million inhabitants and about 200 breweries. Many of them are microbreweries or brewpubs.

Ireland
Ireland has a long history of brewing and in the past two decades, there has been a resurgence in craft breweries. Although the Irish market remains dominated by three multinational brewing concerns (Diageo, Heineken and C&C), there have been four so-called waves of growth in the Irish craft beer market. The number of microbreweries in Ireland had risen from 15 in 2012 to over 72 by 2017. Macro breweries have pursued a policy of forcing craft taps out of pubs, through the use of incentives such as free or discounted kegs offered to publicans to replace craft brewery taps with their own.

Italy
In recent years, many microbreweries have opened in Italy, due to increasing beer popularity among young people. According to Coldiretti, microbreweries have grown in ten years by 1900%. There are more than 900 microbreweries active in Italy.

Norway
After Oslo Microbrewery was established in 1989, the number of microbreweries in Norway has expanded rapidly and sharply in the recent decades. Interest and expertise among Norwegians about craft brewed beer has risen sharply in a short time, and the old brewery traditions of this country are revived and the traditional brewing yeast kveik rediscovered. However, most craft beers are brewed by imported recipes. Local microbreweries are scattered across Norway, from Lindesnes in the very south, and to the northernmost microbrewery in the world, Svalbard Bryggeri at Svalbard.

Russia
Craft brewing gained popularity in Russia in the mid-2010s. Local craft brews typically sell for between 200 and 300 roubles ($3–4) a pint. At least two dozen craft bars have opened in Moscow since the summer of 2014, serving Russian and foreign microbrews. As of 2021 there are about 250 independent craft breweries in Russia, but the share of craft beer in sales was only 1.5%.

Spain

In Spain in 2011, the newspaper El País reported a "revolution is occurring in craft beer" (cervezas artesanales) and more recently that by 2013 the trend had extended to the autonomous communities of Catalonia, Valencia, Basque Country, Navarre and Madrid.

Sweden
In Sweden, microbreweries have existed since around 1995. Today, the market is flourishing with many of the nation's regions and cities having their own breweries, such as Gotlands Bryggeri, Jämtlands Bryggeri, Helsingborgs Bryggeri and Wermlands Brygghus. Stefan Persson, the CEO of Swedish clothing chain H&M, has his own microbrewery on his estate in England.

United Kingdom
The term "microbrewery" originated in the UK in the late 1970s to describe the new generation of small breweries that focused on producing traditional cask ale independently of major brewers or pub chains. In 1972, Martin Sykes established Selby Brewery as the first new independent brewing company for 50 years. "I foresaw the revival in real ale, and got in early", he said. Another early example was the Litchborough Brewery founded by Bill Urquhart in 1974. Alongside commercial brewing, training courses and apprenticeships were offered by Litchborough, with many of the UK movement's early pioneers passing through its courses prior to setting up their own breweries.

Before the development of large commercial breweries in the UK, beer would have been brewed on the premises from which it was sold. Alewives would put out a sign—a hop pole or ale-wand—to show when their beer was ready. The medieval authorities were more interested in ensuring adequate quality and strength of the beer than discouraging drinking. Gradually men became involved in brewing and organized themselves into guilds such as the Brewers Guild in London of 1342 and the Edinburgh Society of Brewers in 1598; as brewing became more organized and reliable many inns and taverns ceased brewing for themselves and bought beer from these early commercial breweries. However, there were some brewpubs which continued to brew their own beer, such as the Blue Anchor in Helston, Cornwall, which was established in 1400 and is regarded as the oldest brewpub in the UK. In the UK during the 20th century, most of the traditional pubs which brewed their own beer in the brewhouse round the back of the pub, were bought out by larger breweries and ceased brewing on the premises. By the mid-1970s, only four remained: All Nations (Madeley, Shropshire), The Old Swan (Netherton, West Midlands), the Three Tuns (Bishop's Castle, Shropshire) and the Blue Anchor pub (Helston, Cornwall).

The trend toward larger brewing companies started to change during the 1970s, when the popularity of the Campaign for Real Ale (CAMRA)'s campaign for traditional brewing methods, and the success of Michael Jackson's World Guide to Beer encouraged brewers in the UK, such as Peter Austin, to form their own small breweries or brewpubs. In 1979, a chain of UK brewpubs, known as the "Firkin" pubs, started, running to over one hundred at the chain's peak; however, the chain was sold and eventually its pubs ceased brewing their own beer.

Some British brewpubs specialize in ale, while others brew continental lagers and wheat beers. The Ministry of Ales, Burnley; The Masons Arms in Headington, Oxford; The Brunswick Inn, Derby (in 2010, half of the beers sold by the establishment were brewed on-site); The Watermill pub, Ings Cumbria; and the Old Cannon Brewery, Bury St Edmunds are some examples of small independent brewpubs in the UK.

The city of Bristol was identified by The Guardian in May 2014 as an area where the microbrewery industry had flourished. Ten brewpubs, such as Zerodegrees, The Tobacco Factory, Copper Jacks Crafthouse and The Urban Standard, were identified as thriving Bristol craft beer establishments.

The East End of London has also been a place for speciality craft beers and unique independent pubs and breweries. Again The Guardian has a list of Craft Beer pubs in East London with local East End tour companies also showing the distinct food and craft beer pubs to London visitors with Craft Beer Tours.

In the UK there are no firm criteria for what defines a "craft beer". In 2019 CAMRA allowed craft keg beers to be sold at its Great British Beer Festival for the first time. Festival organiser Catherine Tonry said: "People coming to the festival love beer in all forms and types of dispense."

Jordan
Jordan has several companies producing beer, the oldest being the Jordan Brewery Company, which built the first Amstel beer factory outside the Netherlands in 1958 in Zarqa, and which also produces Petra, the oldest local brew of Jordan. Jordan's first microbrewery, Carakale Brewery, was established in 2010 in Fuheis.

Turkey
In Turkey, craft beers became popular in present-day; Gara Guzu, Feliz Kulpa, Antiochs, Pablo and Graf are some Turkish craft beer brands.

Canada
By the early 1980s, 97% of Canadian beer was produced by Labatt and Molson. The first microbrewery was the short-lived Horseshoe Bay Brewery, which was opened in 1981 by Frank Appleton and John Mitchell next to the Troller Pub in North Vancouver. It closed after a year, but Mitchell and Appleton, along with Paul Hadfield, opened the Spinnaker Brewpub in Victoria in 1984. A number of other microbreweries subsequently opened between 1984 and 1987, including Granville Island (Vancouver), Big Rock (Calgary), Brick (Waterloo, Ontario), Upper Canada (Toronto), and Wellington County (Guelph, Ontario).

Over the next twenty years there was steady if not spectacular growth, and by 2006 there were 88 small breweries across Canada, most of them in British Columbia, Québec and Ontario. In the second decade of the century, breweries began to appear in every province at an exponential rate, and by 2018, there were over 700 breweries across Canada producing more than 20 million hectolitres. Several provinces have associations representing craft brewers, including the Ontario Craft Brewers (OCB), and the BC Craft Brewers Guild.

Since it is a provincial, not a federal, responsibility to regulate the sale of alcohol, the exact definition of small brewery, microbrewery, macrobrewery and nanobrewery, which is defined by the number of hectolitres produced, varies from province to province.

Several of the more successful microbreweries have been bought by MolsonCoors, AB InBev, and Sapporo, including Granville Island (Vancouver), Mill Street (Toronto), and Creemore Springs (Creemore, Ontario); although the new owners often claim that these operations are still craft breweries, their membership in the relevant provincial craft brewers' association is immediately terminated due to rules requiring independent ownership.

Mexico
In the 1990s craft beer began being produced and consumed in central Mexico, with the trend spreading throughout the country. The main producers are in Baja California, Jalisco and Mexico City. Most beer produced is exported to the United States, and the development of the craft beer industry was not aided by the presence of two large beer consortia in the country. In 2009, craft beer accounted for only 0.05% of total production. The National Association of Craft Beer Producers (Asociación Nacional de Creadores de Cerveza Artesanal) was established to support and promote the industry in Mexico.

United States
In the US, the craft beer movement was revived in 1965—subsequent to an earlier American era—when Fritz Maytag acquired the Anchor Brewing Company in San Francisco, thereby saving it from closure. American craft beer drinkers tend to have higher average incomes and demographically skew white, male, and generation X; however trends show an increasingly racially and ethnically diverse, female, and millennial demographic profile.

In a June 2014 interview, the owner of an Oregon-based microbrewery explained: "You've got to do more than just make great beer. It's really about innovation, creativity—stepping outside the box of traditional beer marketing", while an employee explained that "heart and soul" is the essence of the operation.

The turnaround of the Anchor Brewing Company in 1965, after it was acquired by Maytag, is considered a turning point for American beer, due to the revival of craft beer in the US, where microbrewing boomed after then-president Jimmy Carter de-regulated the beer market in 1979. During the same period, others turned to homebrewing and eventually a few of these brewers started to produce on a slightly larger scale. For inspiration, they turned to the centuries-old tradition of artisan beer and cask ale production that was continuing in the UK, Germany and Belgium.

The New Albion Brewing Company was founded in 1976 and served as a blueprint for American brewers to build small-scale commercial breweries. The popularity of these products was such that the trend quickly spread and a large number of small breweries were founded, often attached to a bar (known as a "brewpub") where the product could be sold directly. As microbreweries proliferated, some became more than microbreweries, necessitating the creation of the broader category of craft beer. American microbreweries typically distribute through a wholesaler in a traditional three-tier system, others act as their own distributor (wholesaler) and sell to retailers or directly to the consumer through a tap room, attached restaurant, or off-premises sales. Because alcohol control is left up to the states, there are many state-to-state differences in the laws. Following the federal US government shutdown on October 1, 2013, craft beer producers were forced into an activity lull due to the closure of the Alcohol and Tobacco Tax and Trade Bureau (TTB), an arm of the Treasury Department. The TTB is responsible for granting approval for new breweries, recipes, and labels. Interest spread to the US, and in 1982, Grant's Brewery Pub in Yakima, Washington was opened, reviving the US "brewery taverns" of well-known early Americans as William Penn, Samuel Adams and Patrick Henry. Growth was initially slow—the fifth US brewpub (BridgePort Brewing Company in Portland, Oregon) opened in 1984, and Dock Street Brewing Company was founded in Philadelphia, Pennsylvania, in 1985 by Rosemarie Certo and Jeffrey Ware, and continues to operate today with multiple locations in Philadelphia, then Triple Rock in 1986, but the growth since then has been considerable: the Brewers Association reports that in 2012 there were 2,075 regional craft breweries, microbreweries and brewpubs in the US

Craft brewing is most established in the US, where changes to US law laid the foundations for the expansion of craft brewing. The 1978 Carter homebrewing law allowed for small amounts of beer and wine, and, in 1979, Carter signed a bill to deregulate the brewing industry, making it easier to start new breweries, although states could still enact local restrictions. As a result of deregulation, homebrewing became a popular hobby in the 1980s and 1990s, and, in the mid-1990s, homebrewers launched business ventures based on home-based hobby brewing. In 1979, 89 breweries existed in the US—the Brewers Association reports that in March 2013 a total of 2,416 US breweries were in operation, with 2,360 considered craft breweries (98 percent—1,124 brewpubs, 1,139 microbreweries, and 97 regional craft breweries). By 2015, the number of US craft breweries had grown to over 4,000. Additionally, craft brewers sold more than 15,600,000 USbeerbbl of beer, which represented approximately 7.8% of the US market by volume. In 2007 the largest American craft brewery was the Boston Beer Company, makers of Samuel Adams. The West Coast has the most craft breweries and the Deep South has the fewest.

The Brewers Association defines American craft brewers as "small, independent and traditional": "small" is defined as an "annual production of 6 million barrels of beer or less"; "independent" is defined as at least 75% owned or controlled by a craft brewer; and "traditional" is defined as brewing in which at least 50% of the beer's volume consists of "traditional or innovative" ingredients. This definition includes older microbreweries, which traditionally produce small quantities of beer, as well as other breweries of various sizes and specialties.

The Brewers Association defines four markets within American craft brewing: microbreweries, with an annual production less than 15000 USbeerbbl; brewpubs, which sell 25% or more of their beer on site; regional craft breweries, which make between 15000 USbeerbbl and 6000000 USbeerbbl, of which at least 50% is all malt or contains adjuncts that are used only to enhance flavor; and contract brewing companies, which hire other breweries to make their beer.

In March 2014, the Brewer's Association (B.A.) updated the definition of craft beer to remove any references to the use of adjuncts in the brewing process. The change allows long-established breweries, such as Yuengling, to be defined as craft beer. The B.A. statement read: "The idea that brewers who had been in business for generations didn't qualify as 'traditional' simply did not cohere for many members. Brewers have long brewed with what has been available to them. (Since the Brewers Association doesn't define craft beer—that idea remains up to the beer drinker—the definition doesn't differentiate on what type of beer craft brewers brew, as long as the majority of what they make is beer.) The revised definition also provides room for the innovative capabilities of craft brewers to develop new beer styles and be creative within existing beer styles. The revised definition removes the subjective assessment by Brewers Association staff of whether adjuncts 'enhance' or 'lighten' flavor in a particular beer."

The B.A. decision also included an updated mission statement and market share goals for the industry. Association members committed to strive for a goal of 20 percent market share by 2020 and Gary Fish, owner of Deschutes Brewery and 2014 chair of the BA Board, explained:

"The 20-by-20 objective is an aspirational goal for our craft community, with an inspiring symmetry. I'm convinced this goal is within our reach if we, as an industry, continue to focus on our strengths and passions—making and delivering high-quality, innovative, full-flavored beer to craft beer enthusiasts. ... Additionally, by noting a commitment to quality and clarifying the place of homebrewers and brewing enthusiasts, we further acknowledge the critical role each plays in the health and growth of the craft brewing industry."

The Brewers Association reported the production of craft beer has doubled between 2011 and 2016, with the number of breweries growing from 2,000 in 2011 to 5,200 in 2016. The craft breweries are also seeing an increase in beer tourism, seasonal brews, and a marketing effort to get more women involved in beer production.

title: Craft beer