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Declension

In linguistics, declension (verb: to decline) is the changing of the form of a word, generally to express its syntactic function in the sentence, by way of some inflection. Declensions may apply to nouns, pronouns, adjectives, adverbs, and determiners to indicate number (e.g. singular, dual, plural), case (e.g. nominative case, accusative case, genitive case, dative case), gender (e.g. masculine, neuter, feminine), and a number of other grammatical categories. Meanwhile, the inflectional change of verbs is called conjugation.

Declension occurs in many of the world's languages. It is an important aspect of language families like Quechuan (i.e., languages native to the Andes), Indo-European (e.g. German, Icelandic, Lithuanian, Latvian, Slavic, Sanskrit, Latin, Ancient and Modern Greek, Albanian, Romanian, Kurdish, Classical and Modern Armenian), Bantu (e.g. Swahili, Zulu, Kikuyu), Semitic (e.g. Modern Standard Arabic), Finno-Ugric (e.g. Hungarian, Finnish, Estonian), and Turkic (e.g. Turkish).

Old English was an inflectional language, but largely abandoned inflectional changes as it evolved into Modern English. Though traditionally classified as synthetic, Modern English has moved towards a mostly analytic language.

English-speaking perspective
Unlike English, many languages use suffixes to specify subjects and objects and word cases in general. Inflected languages have a freer word order than modern English, an analytic language in which word order identifies the subject and object. As an example, even though both of the following sentences consist of the same words, the meaning is different:
 * "The dog chased a cat."
 * "A cat chased the dog."

Hypothetically speaking, suppose English were a language with a more complex declension system in which cases were formed by adding the suffixes:
 * - (for nominative singular), - (genitive), - (dative), - (accusative), - (locative), - (instrumental), - (vocative), - (ablative)

The first sentence above could be formed with any of the following word orders and would have the same meaning:
 * "The dog chased a cat."
 * "A cat chased the dog."
 * "Chased a cat the dog."

As a more complex example, the sentence: becomes nonsensical in English if the words are rearranged (because there are no cases):
 * Mum, this little boy's dog was chasing a cat down our street!
 * A cat was down our street chasing dog this little boy's mum!

But if English were a highly inflected language, like Latin or some Slavic languages such as Croatian, both sentences could mean the same thing. They would both contain five nouns in five different cases: mum – vocative (hey!), dog – nominative (who?), boy – genitive (of whom?), cat – accusative (whom?), street – locative (where?); the adjective little would be in the same case as the noun it modifies (boy), and the case of the determiner our would agree with the case of the noun it determines (street).

Using the case suffixes invented for this example, the original sentence would read:
 * Mum, this little boy dog was chasing a cat down our street!

And like other inflected languages, the sentence rearranged in the following ways would mean virtually the same thing, but with different expressiveness:
 * A cat was down our street chasing dog this little boy, mum!
 * Mum, down street our a cat was chasing this little boy dog!

Instead of the locative, the instrumental form of "down our street" could also be used:
 * Mum, this little boy dog our street was chasing a cat!
 * A cat was, mum, our street chasing dog this little boy
 * Our street a cat was chasing dog this little boy, mum!

Different word orders preserving the original meaning are possible in an inflected language, while modern English relies on word order for meaning, with a little flexibility. This is one of the advantages of an inflected language. The English sentences above, when read without the made-up case suffixes, are confusing.

These contrived examples are relatively simple, whereas actual inflected languages have a far more complicated set of declensions, where the suffixes (or prefixes, or infixes) change depending on the gender of the noun, the quantity of the noun, and other possible factors. This complexity and the possible lengthening of words is one of the disadvantages of inflected languages. Notably, many of these languages lack articles. There may also be irregular nouns where the declensions are unique for each word (like irregular verbs with conjugation). In inflected languages, other parts of speech such as numerals, demonstratives, adjectives, and articles are also declined.

History
It is agreed that Ancient Greeks had a "vague" idea of the forms of a noun in their language. A fragment of Anacreon seems to confirm this idea. Nevertheless, it cannot be concluded that the Ancient Greeks actually knew what the cases were. The Stoics developed many basic notions that today are the rudiments of linguistics. The idea of grammatical cases is also traced back to the Stoics, but it is still not completely clear what the Stoics exactly meant with their notion of cases.

Modern English
In Modern English, the system of declensions is so simple compared to some other languages that the term declension is rarely used.

Nouns
Most nouns in English have distinct singular and plural forms. Nouns and most noun phrases can form a possessive construction. Plurality is most commonly shown by the ending -s (or -es), whereas possession is always shown by the enclitic -'s or, for plural forms ending in s, by just an apostrophe.

Consider, for example, the forms of the noun girl. Most speakers pronounce all forms other than the singular plain form (girl) exactly the same.

By contrast, a few irregular nouns (like man/men) are slightly more complex in their forms. In this example, all four forms are pronounced distinctly.

For nouns, in general, gender is not declined in Modern English. There are isolated situations where certain nouns may be modified to reflect gender, though not in a systematic fashion. Loan words from other languages, particularly Latin and the Romance languages, often preserve their gender-specific forms in English, e.g. alumnus (masculine singular) and alumna (feminine singular). Similarly, names borrowed from other languages show comparable distinctions: Andrew and Andrea, Paul and Paula, etc. Additionally, suffixes such as -ess, -ette, and -er are sometimes applied to create overtly gendered versions of nouns, with marking for feminine being much more common than marking for masculine. Many nouns can actually function as members of two genders or even all three, and the gender classes of English nouns are usually determined by their agreement with pronouns, rather than marking on the nouns themselves.

There can be other derivations from nouns that are not considered declensions. For example, the proper noun Britain has the associated descriptive adjective British and the demonym Briton. Though these words are clearly related, and are generally considered cognates, they are not specifically treated as forms of the same word, and thus are not declensions.

Pronouns
Pronouns in English have more complex declensions. For example, the first person "I":

Whereas nouns do not distinguish between the subjective (nominative) and objective (oblique) cases, some pronouns do; that is, they decline to reflect their relationship to a verb or preposition, or case. Consider the difference between he (subjective) and him (objective), as in "He saw it" and "It saw him"; similarly, consider who, which is subjective, and the objective whom (although it is increasingly common to use who for both).

The one situation where gender is still clearly part of the English language is in the pronouns for the third person singular. Consider the following:

The distinguishing of neuter for persons and non-persons is peculiar to English. This has existed since the 14th century. However, the use of singular they is often restricted to specific contexts, depending on the dialect or the speaker. It is most typically used to refer to a single person of unknown gender (e.g. "someone left their jacket behind") or a hypothetical person where gender is insignificant (e.g. "If someone wants to, then they should"). Its use has expanded in recent years due to increasing social recognition of persons who do not identify themselves as male or female (see gender-nonbinary). The singular they still uses plural verb forms, reflecting its origins.

Adjectives and adverbs
Some English adjectives and adverbs are declined for degree of comparison. The unmarked form is the positive form, such as quick. Comparative forms are formed with the ending -er (quicker), while superlative forms are formed with -est (quickest). Some are uncomparable; the remainder are usually periphrastic constructions with more (more beautiful) and most (most modestly). See degree of comparison for more.

Adjectives are not declined for case in Modern English (though they were in Old English), nor number nor gender.

Determiners
The demonstrative determiners this and that are declined for number, as these and those.

The article is never regarded as declined in Modern English, although formally, the words that and possibly she correspond to forms of the predecessor of the (sē m., þæt n., sēo f.) as it was declined in Old English.

Latin
Just as verbs in Latin are conjugated to indicate grammatical information, Latin nouns and adjectives that modify them are declined to signal their roles in sentences. There are five important cases for Latin nouns: nominative, genitive, dative, accusative, and ablative. Since the vocative case usually takes the same form as the nominative, it is seldom spelt out in grammar books. Yet another case, the locative, is limited to a small number of words.

The usual basic functions of these cases are as follows:
 * Nominative case indicates the subject.
 * Genitive case indicates possession and can be translated with 'of'.
 * Dative case marks the indirect object and can be translated with 'to' or 'for'.
 * Accusative case marks the direct object.
 * Ablative case is used to modify verbs and can be translated as 'by', 'with', 'from', etc.
 * Vocative case is used to address a person or thing.

The genitive, dative, accusative, and ablative also have important functions to indicate the object of a preposition.

Given below is the declension paradigm of Latin puer 'boy' and puella 'girl':

From the provided examples we can see how cases work:

liber puerī

book boy.GEN

the book of the boy

puer puellae rosam dat

boy.NOM girl.DAT rose.ACC give.3SG.PRES

the boy gives the girl a rose

Sanskrit
Sanskrit, another Indo-European language, has eight cases: nominative, vocative, accusative, genitive, dative, ablative, locative and instrumental. Some do not count vocative as a separate case, despite it having a distinctive ending in the singular, but consider it as a different use of the nominative.

Sanskrit grammatical cases have been analyzed extensively. The grammarian Pāṇini identified six semantic roles or karaka, which correspond closely to the eight cases: For example, consider the following sentence:
 * agent (, related to the nominative)
 * patient (, related to the accusative)
 * means (, related to the instrumental)
 * recipient (, related to the dative)
 * source (, related to the ablative)
 * relation (, related to genitive)
 * locus (, related to the locative)
 * address (, related to the vocative)

{from the tree} {a leaf} {to the ground} falls

"a leaf falls from the tree to the ground"

Here leaf is the agent, tree is the source, and ground is the locus. The endings -aṁ, -at, -āu mark the cases associated with these meanings.

Verse 37 of the Rāmarakṣāstotram gives an example of all 8 types of declensions in Sanskrit for the singular proper noun Rāma.

Declension in specific languages

 * Albanian declension
 * Arabic ʾIʿrab
 * Basque declension
 * Urdu and Hindi declension

Greek and Latin

 * Ancient Greek and Latin First declension
 * Ancient Greek and Latin Second declension
 * Ancient Greek and Latin Third declension
 * Greek declension
 * Latin declension

Celtic languages

 * Irish declension

Germanic languages

 * Dutch declension system
 * German declension
 * Gothic declension
 * Icelandic declension
 * Middle English declension

Baltic languages

 * Latvian declension
 * Lithuanian declension

Slavic languages

 * Bosnian, Croatian, Montenegrin and Serbian declension
 * Czech declension
 * Polish declension
 * Russian declension
 * Slovak declension
 * Slovene declension
 * Ukrainian declension

Uralic languages

 * Finnish noun cases

title: Declension


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Talk:Dative case

I don't see what Tsez has to do in this article. While I appreciate the addition, I believe that it serves no purpose to explain the dative of a language that only 7000 people in the world can understand. Mixaelus 20:14, 22 June 2006 (UTC)
 * In my opinion it's a good example to show for what the dative case is used in other non-IE languages, in this case, it also has a local function, and it's used for subjects with verbs of perception and feeling. This works similar with other Northeast Caucasian languages, perhaps also with Northwest ones... I'm not sure, but this could even be a common feature among absolute/ergative languages. Thus, it represents far more than just 7000 speakers. I just happen to know more about Tsez than about any other Caucasian or ergative language. — N-true 21:07, 22 June 2006 (UTC)
 * Can you please point that out in the respective section? We don't want to confuse our readers. Or, better yet, change the heading to 'Dative Case in Non-Indo-European languages'.  It's up to you. Mixaelus 04:14, 30 July 2006 (UTC)
 * Hm, okay, might be a good idea. — N-true 11:19, 30 July 2006 (UTC)

I gave the rest of the examples for Greek. The dative in Greek has other locative/temporal functions as well, which I should be adding soon. For the time being, however, please correct as you see appropriate. Mixaelus 20:53, 6 June 2006 (UTC)

The article for "Indirect object" links here, but no example of the distinction between direct and indirect object is given....

I added the example of "the dativus instrumenti" in Classical Greek. If it's inaccurate, please do fix it. Thanks -Yazeed.

Now that I added the bit about "methinks" as an example of dative case in English, I find myself doubting whether I should have done so. Is it not an example of excessive anglocentrism? While this Wikipedia's primary language is English, it may seem a bit presumptuous to illustrate perfectly universal categories and topics (such as "dative case") with examples from the English language. Or not? I'm not sure. --AV

- "This is the English Wikipedia". While there are probably many multilingual users, English is the only language we should assume that the readers possess. Examples in English *are* most universal, given that assumption.

I'm also of the opinion that provoking people to think more about the structures and idiosyncracies of their native language is a good thing. -- Paul Drye -- I think the English "methinks" is a bit of a historical oddity, and while it is useful as a historical tidbit, it is a confusing example. I think giving an example from Latin, or some other language with cases (Russian, Finish, etc. -- take your pick) would be more useful. Especially since the Old English that "methinks" derives from is probably different from the modern word "methinks". -- SJK - The main page says that the Dative has dissapeared from English grammar. This I'd agree with only in the sense that the dative has no inflection distinct from the accusative case. It occurs in such sentences as 'He gave me it' and 'He built me a snowman'. I boths examples 'me' is dative. -- Karl Palmen

Who says "he gave me it"? That sounds (to my ears, anyway) really colloquial and ungrammatical. Or is it just me?

Colloquial, yes. Awkward, yes. But it is indeed grammatical. You would say, for example, "he gave me that", which is an identical construction with a different pronoun. --LDC

Everyone says "he gave me it" or at any rate "he gave me one", "he gave me that", "he gave me more than I asked for", "she wrote me a letter", etc. Why do you think that it is it awkward? I use sentences like "My wife bought me a doughnut" all the time (dative "me"). Are you saying that you would use "My wife bought a doughnut for me" in preference ? Surely not. -- Derek Ross

 * Of course not, and you missed my point. I replaced "He gave me it" with "He gave me that" in the example in the article, because "He gave me it" is very awkward and colloquial.  The other uses of the dative "me" that you specified are not colloquial or awkward, and are perfectly legitimate in formal speech.

Yes, that's probably the best thing to do. I have no idea why people don't generally say "he gave me it" when it is parallel to the other examples. Ask Steven Pinker or George Lakoff. --LDC

 * I think you'll find that the answer to any question that begins with "I wonder why English...." is "Because English is a mess." :) -- Paul Drye

I sometimes use "he gave me it", but not very often. I use "he gave it me" as well, missing out the "to".
 * "he gave it me" is not grammatical to my ear. Netrapt (talk) 13:47, 24 January 2008 (UTC)

Also,
 * Roughly 25% of German verbs, generally those pertaining directly to an act of giving, require the dative for their direct objects.... Ich gebe ihr... ("I give her...")

I may be wrong, but at least in this example isn't ihr the indirect object, with whatver's being given the direct object? --195.188.51.100 14:21, 29 November 2005 (UTC)

The examples using geben and sagen are both incorrect. In each case, the objects cited are in the dative because they are INdirect objects. This is obvious, because neither example makes sense without also having a direct object (in the accusative). "Ich gebe ihr (ind obj:dative) das Buch (dir obj:akk)" and "Sag uns (ind obj:dat) deine Telefonnummer (dir obj:akk)". In both cases, the direct object could be an entire subordinate clause.

While there are German verbs that have (apparently) direct objects in the dative, I believe that most verbs pertaining to giving require both indirect and direct objects, in the dative and accusative cases, respectively.

From the front page today: "The name Éire is the dative form in modern Irish Gaelic of the name for the goddess Eriu, a mythical figure who aided the Gaels conquer Ireland as described in the Book of Invasions."

I did not see Gaelic or Irish on the list. (What about Scottish?) I leave it to the experts here to work out the details. Leonard G. 04:34, 14 Jul 2004 (UTC)

First sentence wrong?
The first sentence indicates that the dative case is used to mark a direct object. However, the rest of the article implies that the dative case is used for the indirect object! Someone who knows a bit more about this should clarify this. Perhaps a section comparing the dative and accustive cases would be in order, along with their correlations with direct and indirect objects. --Scorpiuss

Yes, the introduction is wrong. 217.30.32.17 (talk) 14:56, 20 October 2009 (UTC)

German examples
The two German examples given in the article, while not technically incorrect, are somewhat awkward:

 * Ich gebe das Buch zum Kassierer
 * Ich habe das Buch an meinen Freund geschenkt.

A German speaker would say neither of these things - rather, they'd say "Ich gebe das Buch dem Kassierer" and "Ich habe das Buch meinem Freund geschenkt". -- Schnee (cheeks clone) 22:25, 16 January 2006 (UTC)

Merge Dative construction here
Please see discussion on the other article's talk page. CapnPrep 16:10, 10 August 2007 (UTC)

Greek Dative Usages
Another usage that could be included is the dative of reference, which denotes the person in whose opinion a statement holds true, for example, "ἔχθιστος δέ μοί ἐσσι διοτρεφέων βασιλήων" "to me you are the most hateful of the Zeus-cherished kings" (Iliad 1.176)

Dative case in Russian and related
I'm not convinced that in a sentence 'I call John', John is the direct object, John is the indirect object here. The direct object is the message you relay to him which is explicit per context as that's usually what a phone call does. Analogous to 'I give John a book' we obtain 'I call John a message.' Or even more explicitly 'I write John a letter'. The person whom one calls is an indirect object I believe, not a direct object. Rajakhr (talk) 05:54, 4 January 2009 (UTC)

 * But unlike your examples with give and write, "I call a message (to John)" and "I call John a message" are not grammatical. So "a message" is not the direct object. This does not mean that "John" is necessarily the direct object in "I call John", but I don't see any good reasons to say otherwise. (For example, one might be tempted to say that "John" is an indirect object in "I wrote John" because you can also say "I wrote to John". But "I call to John" does not mean the same thing as "I call John".) CapnPrep (talk) 17:27, 4 January 2009 (UTC)
 * 'I call John a message' is grammatical I'd reckon, it's just not said a lot as 'calling' implies what is said. However saying 'I just called John a very angry message after he ate all children in the school.' is done more often as the angry part of if is not implied by the calling itself. The two examples you gave, the only language I feel I have a sufficient command over that uses a dative case is German, and there with the verb 'anrufen', using the dative or accusative case means a very slight nuance which is comparable to 'I call to John' and 'I call John', I think the Russian use of the dative is semantically more akin to 'I call to John' but the presence of the 'to' in English connotates a very marginal difference. Rajakhr (talk) 09:02, 5 January 2009 (UTC)

 * I'm afraid it's still not grammatical ("*I just called John a very angry message…"). It just doesn't work with this meaning of call (= phone). CapnPrep (talk) 12:18, 5 January 2009 (UTC)
 * I'd say that is unusual / poetic but grammatical. Regardless, a native speaker of Russian has just informed me that in Russian, it is possible to put the message you relay with the verb as ditransitive, which is then put into the accusative case, which makes it all but completely out of question that the person whom you call to is the indirect object, not the direct and the message you put through is the direct object, in Russian at least. Rajakhr (talk) 17:08, 6 January 2009 (UTC)

The Dative Case in English
"In British usage, "Give it to me" can be rendered as either "Give me it" or in American usage "Give it me."" I am fairly certain that "Give it me" is not correct grammar in the English language. I cannot think of a situation in English where an indirect object is not preceded by a preposition. I suggest that the quoted text be removed. Philmac (talk) 04:28, 3 July 2009 (UTC)

--- BY Anirban Nag.......... —Preceding unsigned comment added by 113.21.72.31 (talk) 06:45, 25 November 2009 (UTC)

finalis examples in Greek
How are these delineated from the commodi? The king benefits from my fighting; honor benefits from my death. Maybe other examples should be used in the finalis case. -- 92.229.98.128 (talk) 01:33, 24 February 2010 (UTC)

Slavic dative
The section on Slavic begins with discussion of endings, something that's not the most important thing. For Latin and Greek endings are not discussed at all. Croatian (my native language) uses possessive and ethical dative a lot, Greek and Latin examples could be translated almost word-by-word with the same meaning. I think the section should be reworked emphasizing use of datives, which is as complex as in Greek (actually, slightly less so, since most Slavic languages have more cases than Greek and they take some functions of the Greek dative. Opinions? dnik ► 10:44, 29 September 2010 (UTC)

Deletion of Armenian section
I deleted the Armenian section because it was completely wrong.

grandexandi (talk) 12:02, 15 February 2013 (UTC)

Subdivision by language
I think it's not particularly helpful to have only sections by language. For instance, the ethic dative is a rather universal concept which can be used to interpret linguistic phenomena in several languages. Some instances come straight from Latin, but not all of them. --Nemo 21:09, 11 October 2013 (UTC)

Perhaps no one is an expert in Greek, Latin, Lithuanian and German but these subsections focus on different aspects. In German we have the grammar, in Greek and Latin the different modes and in Lithuanian the resemblance to proto-Indoeuropean.Skamnelis (talk) 15:28, 25 March 2014 (UTC)

Is dative a single case?
It is clear from the examples in Greek, Latin and German that the dative has other uses besides giving. There are even uses not included, such as the locative dative (dative of time). A line in the introduction mentions assimilation of other now-extinct cases. Are there any hypotheses of what these were and how the dative evolved? Or is the name "dative" misleading and it is - and was, indeed - a single case pertaining to indirect objects?Skamnelis (talk) 14:55, 25 March 2014 (UTC)

Examples section
An examples section would be helpful in this article. There is one in the nominative case article! Adlihtam (talk) 14:28, 6 September 2015 (UTC) Adlihtam (talk) 14:28, 6 September 2015 (UTC)

I have added a new sub-section that has more examples of Dative Case. I included examples in every gender and in plural. I also included whether the chanign word was a DIE word or an EIN to help with clarity. I included a very brief example of Accusative and Dative case being compared because to show that case is important, and one sentence can have a different meaning if the only thing that is changed is the case. JuliaCostantino (talk) — Preceding undated comment added 03:59, 9 February 2022 (UTC)

Dative object not direct object
The dative object in German cannot be a direct object. If it were a direct object, it would require the accusative case and passivisation would be possible. Verbs with the dative object are intransitive in German. — Preceding unsigned comment added by 84.26.183.218 (talk) 15:37, 2 November 2019 (UTC)

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

title: Talk:Dative case


text:
Daffynition

A daffynition (a portmanteau blend of daffy and definition) is a form of pun involving the reinterpretation of an existing word, on the basis that it sounds like another word (or group of words). Presented in the form of dictionary definitions, they are similar to transpositional puns, but often much less complex and easier to create.

Under the name Uxbridge English Dictionary, making up daffynitions is a popular game on the BBC Radio 4 comedy quiz show I'm Sorry I Haven't a Clue.

A lesser-known subclass of daffynition is the goofinition, which relies strictly on literal associations and correct spellings, such as "lobster = a weak tennis player". This play on words is similar to Cockney rhyming slang.

Examples

 * acrostic: An angry bloodsucking arachnid. (a-cross-tick)
 * American: A happy cylindrical food container. (a-merry-can)
 * apéritif: A set of dentures. (a-pair-of-teeth)
 * avoidable: What a bullfighter tries to do. (avoid-a-bull)
 * buccaneer: too much to pay for corn ([a]-buck-an-ear)
 * dandelion: A fashionably dressed big cat (dandy-lion)
 * decadent: Possessing only ten teeth. (deca-dent)
 * denial: A river in Africa. (the-Nile)
 * devastation: Where people wait for buses. (the-bus-station)
 * dilate: live long (die-late)
 * euthanasia: Teenagers in the world's largest continent. (youth-in-Asia)
 * fortunate: Consumption of an expensive meal. (fortune-ate)
 * impolite: A flaming goblin. (imp-alight)
 * indistinct: where one places dirty dishes (in-the-sink)
 * information: how geese fly (in-formation)
 * innuendoes: Italian suppositories. (in-you-end-os)
 * insolent: Fallen off the Isle of Wight ferry. (in-Solent)
 * isolate: Me not on time. (I-(am)-so-late)
 * legend: A foot. (leg-end)
 * oboe: A French tramp. (hobo)
 * paradox: Two doctors. (pair-of-docs) or where one ties two boats. (Pair of docks)
 * pasteurise: Too far to see. (past-your-eyes)
 * protein: In favour of youth. (pro-teen)
 * propaganda: A gentlemanly goose. (proper-gander) or to look at something very carefully (proper-gander, where gander is slang for looking)
 * recycle: To repair a bicycle, or obtain a replacement bicycle. (re-cycle)
 * relief: What trees do in Spring. (re-leaf)
 * specimen: An Italian astronaut. (spaceman)
 * symmetry: A South African or New Zealand graveyard. (cemetery)

title: Daffynition


text:
List of football clubs in the Netherlands

The Dutch Football League is organized by the Royal Dutch Football Association (KNVB, Koninklijke Nederlandse Voetbalbond).The most successful teams are Ajax (36), PSV (24) and Feyenoord (16). Important teams of the past are HVV (10 titles), Sparta Rotterdam (6 titles) and Willem II (3 titles).

The annual match that marks the beginning of the season is called the Johan Cruijff Schaal (Johan Cruyff Shield). Contenders are the champions and the cup winners of the previous season.

Former Dutch league teams

 * Koninklijke HFC
 * AVV RAP (of Amsterdam) were the first official champions of the Netherlands in 1899. The club however became a Cricket club in 1916 following a total of 5 national football titles.
 * Fortuna 54 (of Geleen) and Sittardia (of Sittard) merged to form Fortuna Sittard in 1968.
 * Blauw Wit, DWS and De Volewijckers merged to form FC Amsterdam in 1972, which ceased to exist in 1982.
 * PEC and the Zwolsche Boys merged to form PEC Zwolle in 1971, which became FC Zwolle in 1990.
 * Sportclub Enschede and the Enschedese Boys merged to form FC Twente in 1965.
 * DOS, Elinkwijk and Velox merged to form FC Utrecht in 1970.
 * GVAV became FC Groningen in 1971.
 * Alkmaar 54 and FC Zaanstreek merged to form AZ in 1967.
 * Roda Sport and Rapid JC merged to form Roda JC in 1962.
 * BVC Rotterdam and BVC Flamingos merged to form Scheveningen Holland Sport in 1954, which merged with ADO in 1971 to form FC Den Haag, and became ADO Den Haag in 1996.
 * SVV and Dordrecht '90 merged to form SVV/Dordrecht '90 in 1991. The club has since been renamed FC Dordrecht.
 * VC Vlissingen (from Flushing) became a professional club in 1990, changed its name to VCV Zeeland a year later, and became an amateur club again in 1992.
 * FC Wageningen (founded in 1911) won the Dutch cup in 1939 and 1948, joined the Dutch professional league when it was formed in 1954, and remained professional until the club went bankrupt in 1992.
 * HVC of Amersfoort was formed in 1905, joined the league in 1954, was renamed to SC Amersfoort in 1973 and went bankrupt in 1982.
 * Fortuna Vlaardingen (formed in 1904) joined the professional league in 1955, was renamed to FC Vlaardingen in 1974 and went bankrupt in 1981.
 * HFC Haarlem (formed in 1889) joined the professional league in 1954 and remained professional until the club went bankrupt in 2010.
 * RBC Roosendaal (formed in 1927) joined the professional league in 1955 till 1971 and 1983 and remained professional until the club went bankrupt in 2011.
 * AGOVV Apeldoorn (formed in 1913) joined the professional league in 1954 till 1971, returned to professional soccer on 1 July 2003, and went bankrupt in 2013.
 * SC Veendam (formed in 1894) joined the professional league in 1954, and went bankrupt in 2013.
 * Zwart-Wit '28 won the national amateur championship in 1971 and the national cup for women in 2000. Went bankrupt in 2004.


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Dragon 32/64

The Dragon 32 and Dragon 64 are home computers that were built in the 1980s. The Dragons are very similar to the TRS-80 Color Computer, and were produced for the European market by Dragon Data, Ltd., initially in Swansea, Wales before moving to Port Talbot, Wales (until 1984) and by Eurohard S.A. in Casar de Cáceres, Spain (from 1984 to 1987), and for the US market by Tano Corporation of New Orleans, Louisiana. The model numbers reflect the primary difference between the two machines, which have 32 and 64 kilobytes of RAM, respectively.

Dragon Data introduced the Dragon 32 microcomputer in August 1982, followed by the Dragon 64 a year later. Despite initial success, the Dragon faced technical limitations in graphics capabilities and hardware-supported text modes, which restricted its appeal in the gaming and educational markets. Dragon Data collapsed in 1984 and was acquired by Spanish company Eurohard S.A. However, Eurohard filed for bankruptcy in 1987.

The Dragon computers were built around the Motorola MC6809E processor and featured a composite monitor port, allowing connection to (at the time) modern TVs. They used analog joysticks and had a range of peripherals and add-ons available. The Dragon had several high-resolution display modes, but limited graphics capabilities compared to other home computers of the time.

The Dragon came with a Microsoft BASIC interpreter in ROM, which allowed instant system start-up. The Dragon 32/64 was capable of running multiple disk operating systems, and a range of popular games were ported to the system.

Overall, the Dragon computers were initially well-received but faced limitations that hindered their long-term success.

Dragon 32 vs. Dragon 64
Aside from the amount of RAM, the Dragon 64 also has a functional RS-232 serial port which was not included on the Dragon 32. A minor difference between the two Dragon models is the outer case colour; the Dragon 32 is beige and the Dragon 64 is light grey. Besides the case, branding and the Dragon 64's serial port, the two machines look the same. The Dragon 32 is upgradable to Dragon 64. In some cases, buyers of the Dragon 32 found that they actually received a Dragon 64 unit.

Product history
Dragon Data entered the market in August 1982 with the Dragon 32. The Dragon 64 followed a year later. The computers sold well initially and attracted the interest of independent software developers including Microdeal. A companion magazine, Dragon User, began publication shortly after the microcomputer's launch.

Despite this initial success, there were two technical impediments to the Dragon's acceptance. The graphics capabilities trailed behind other computers such as the ZX Spectrum and BBC Micro, a significant shortcoming for the games market. Additionally, as a cost-cutting measure, the hardware-supported text modes only included upper case characters; this restricted the system's appeal to the educational market.

Dragon Data collapsed in June 1984. It was acquired by the Spanish company Eurohard S.A., which moved the factory from Wales to Cáceres and released the Dragon 200 (a Dragon 64 with a new case that allowed a monitor to be placed on top) and the Dragon 200-E (an enhanced Dragon 200 with both upper and lower case characters and a Spanish keyboard), but ultimately filed for bankruptcy in 1987. The remaining stock from Eurohard was purchased by a Spanish electronics hobbyist magazine and given away to those who paid for a three-year subscription, until 1992.

In the United States it was possible to purchase the Tano Dragon new in box until early 2017 from California Digital, a retailer that purchased the remaining stock.

Reception
BYTE wrote in January 1983 that the Dragon 32 "offers more feature for the money than most of its competitors", but "there's nothing exceptional about it". The review described it as a redesigned, less-expensive Color Computer with 32K RAM and better keyboard.

Hardware and peripherals
The Dragon is built around the Motorola MC6809E processor running at 0.89 MHz. It was an advanced 8-bit CPU design, with limited 16-bit capabilities.

It was possible to increase the speed of the computer by using POKE 65495,0 which accelerated the ROM-resident BASIC interpreter, but temporarily disabled proper functioning of the cassette/printer ports. Manufacturing variances mean that not all Dragons were able to function at this higher speed, and use of this POKE could cause some units to crash or be unstable, though with no permanent damage. POKE 65494,0 returned the speed to normal. POKE 65497,0 pushed the speed yet higher but the display was lost until a slower speed was restored.

The Dragon used the SN74LS783/MC6883 Synchronous Address Multiplexer (SAM) and the MC6847 Video Display Generator (VDG). I/O was provided by two MC6821 Peripheral Interface Adapters (PIAs). Many Dragon 32s were upgraded by their owners to 64 KB of memory. A few were further expanded to 128 KB, 256 KB, or 512 KB with home-built memory controllers/memory management units (MMUs).

A broad range of peripherals exist for the Dragon 32/64, and there are add-ons such as the Dragon's Claw which give the Dragons a port that is hardware-compatible with the BBC Micro's user port, though separate software drivers for connected devices must be developed. Although neither machine has a built-in disk operating system (Compact Cassettes being the standard storage mechanism commonly used for machines of the time), DragonDOS was supplied as part of the disk controller interface from Dragon Data Ltd. The versatile external ports, including the standard RS-232 on the 64, also allows hobbyists to attach a diverse range of equipment.

The computer featured a composite monitor port as an alternative to the TV RF output which can be used to connect the Dragon 32 to most modern TVs to deliver a much better picture.

The Dragon used analogue joysticks, unlike most systems of the time which used simpler and cheaper digital systems. Other uses for the joystick ports included light pens.

Tony Clarke and Richard Wadman established the specifications for the Dragon.

The units had a robust motherboard in a spacious case, reminiscent of the BBC Micro, and so were more tolerant of aftermarket modification than some of their contemporaries, which often had their components crammed into the smallest possible space.

Video modes
The Dragon's main display mode is 'black on green' text (the black was, in actuality, a deeper, muddier green). The only graphics possible in this mode are quarter-tile block based.

It also has a selection of five high-resolution modes, named PMODEs 0–4, which alternate monochrome and four-colour in successively higher resolutions, culminating in the black-and-white 256×192 PMODE 4. Each mode has two possible colour palettes – these are rather garish and cause the system to fare poorly in visual comparisons with other home computers of the time. It is also impossible to use standard printing commands to print text in the graphical modes, causing software development difficulties.

Full-colour, scanline-based 64×192 semi-graphics modes are also possible, though their imbalanced resolution and programming difficulty (not being accessible via BASIC) meant they were not often utilised.

Disk systems
First to market was a complete disk operating system produced by Premier Microsystems, located near Croydon. The system was sold as the "Delta" disk operating system; there was a proposal for Dragon to market this as an addon. Dragon did not enter into such an agreement and instead produced the DragonDOS system. The two systems were incompatible.

Delta's lead in availability ensured that software was released in the format, whilst Dragon's "official" status ensured that it, too, gained software published in its format. This led to confusion and frustration, with customers finding they had either purchased a version incompatible with their setup, or that the software was only available for the competing standard.

System software
The Dragon comes with a Microsoft BASIC interpreter in 16 KB of ROM. The BASIC appears to be nearly identical to Tandy Color Computer's Extended Basic with a few changes necessary to interact with the Dragon system.

In common with home computers of the time, the entire operating software was included on a ROM chip; therefore, the system starts instantly when powered up.

Some software providers also produced compilers for BASIC and other languages to produce binary (or "machine") code which would run many times faster and make better use of the small system RAM. Towards the end of its life, Dragon Data produced an assembler/disassembler/editor suite called Dream.

In addition to the DragonDOS disk operating system, the Dragon 32/64 is capable of running several others, including FLEX, and even OS-9 which brought UNIX-like multitasking to the platform. Memory-expanded and MMU-equipped Dragons are able to run OS-9 Level 2.

Games
Initially, the Dragon was reasonably well supported by the major UK software companies, with versions of popular games from other systems being ported to the Dragon. Top-selling games available for the Dragon include Arcadia (Imagine), Chuckie Egg (A&F), Manic Miner and sequel Jet Set Willy (Software Projects), Hunchback (Ocean) and Football Manager (Addictive). There were also companies that concentrated on the Dragon, such as Microdeal. Their character Cuthbert appeared in several games, with Cuthbert Goes Walkabout also being converted for Atari 8-bit and Commodore 64 systems.

Due to the limited graphics modes of the Dragon, converted games had a distinctive appearance, with colour games being usually played on a green or white background (rather than the more common black on other systems) or games with high-definition graphics having to run in black and white.

When the system was discontinued, support from software companies also effectively ended. However, Microdeal continued supporting the Dragon until January 1988. Some of their final games developed for the Dragon in 1987 such as Tanglewood and Airball were also converted for 16-bit machines such as the Atari ST and Amiga.

Differences from the TRS-80 Color Computer
Both the Dragon and the TRS-80 Color Computer are based on a Motorola data sheet design for the MC6883 SAM (MMU) chip for memory management and peripheral control.

The systems are sufficiently similar that a significant fraction of the compiled software produced for one machine will run on the other. Software running via the built-in Basic interpreters also has a high level of compatibility, but only after they are re-tokenized, which can be achieved fairly easily by transferring via cassette tape with appropriate options.

It is possible to permanently convert a Color Computer into a Dragon by swapping the original Color Computer ROM and rewiring the keyboard cable.

The Dragon has additional circuitry to make the MC6847 VDG compatible with European 625-line television standards, rather than the US 525-line NTSC standard, and a Centronics parallel printer port not present on the TRS-80. Some models were manufactured with NTSC video for the US and Canadian markets.

title: Dragon 32/64


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Dark matter

In astronomy, dark matter is a hypothetical form of matter that appears not to interact with light or the electromagnetic field. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be seen. Such effects occur in the context of formation and evolution of galaxies, gravitational lensing, the observable universe's current structure, mass position in galactic collisions, the motion of galaxies within galaxy clusters, and cosmic microwave background anisotropies.

In the standard lambda-CDM model of cosmology, the mass–energy content of the universe is 5% ordinary matter, 26.8% dark matter, and 68.2% a form of energy known as dark energy. Thus, dark matter constitutes 85% of the total mass, while dark energy and dark matter constitute 95% of the total mass–energy content.

Dark matter is not known to interact with ordinary baryonic matter and radiation except through gravity, making it difficult to detect in the laboratory. The most prevalent explanation is that dark matter is some as-yet-undiscovered subatomic particle, such as weakly interacting massive particles (WIMPs) or axions. The other main possibility is that dark matter is composed of primordial black holes.

Dark matter is classified as "cold", "warm", or "hot" according to its velocity (more precisely, its free streaming length). Recent models have favored a cold dark matter scenario, in which structures emerge by the gradual accumulation of particles.

Although the astrophysics community generally accepts dark matter's existence, a minority of astrophysicists, intrigued by specific observations that are not well-explained by ordinary dark matter, argue for various modifications of the standard laws of general relativity. These include modified Newtonian dynamics, tensor–vector–scalar gravity, or entropic gravity. So far none of the proposed modified gravity theories can describe every piece of observational evidence at the same time, suggesting that even if gravity has to be modified, some form of dark matter will still be required.

Early history
The hypothesis of dark matter has an elaborate history. In the appendices of the book Baltimore lectures on molecular dynamics and the wave theory of light where the main text was based on a series of lectures given in 1884, Lord Kelvin discussed the potential number of stars around the Sun from the observed velocity dispersion of the stars near the Sun, assuming that the Sun was 20 to 100 million years old. He posed what would happen if there were a thousand million stars within 1 kiloparsec of the Sun (at which distance their parallax would be 1 milliarcsecond). Lord Kelvin concluded:"Many of our supposed thousand million stars, perhaps a great majority of them, may be dark bodies."In 1906, Henri Poincaré in The Milky Way and Theory of Gases used the French term matière obscure ("dark matter") in discussing Kelvin's work. He found that the amount of dark matter would need to be less than that of visible matter.

The second to suggest the existence of dark matter using stellar velocities was Dutch astronomer Jacobus Kapteyn in 1922. A publication from 1930 points to Swedish Knut Lundmark being the first to realise that the universe must contain much more mass than can be observed. Dutchman and radio astronomy pioneer Jan Oort also hypothesized the existence of dark matter in 1932. Oort was studying stellar motions in the local galactic neighborhood and found the mass in the galactic plane must be greater than what was observed, but this measurement was later determined to be erroneous.

In 1933, Swiss astrophysicist Fritz Zwicky, who studied galaxy clusters while working at the California Institute of Technology, made a similar inference. Zwicky applied the virial theorem to the Coma Cluster and obtained evidence of unseen mass he called dunkle Materie ('dark matter'). Zwicky estimated its mass based on the motions of galaxies near its edge and compared that to an estimate based on its brightness and number of galaxies. He estimated the cluster had about 400 times more mass than was visually observable. The gravity effect of the visible galaxies was far too small for such fast orbits, thus mass must be hidden from view. Based on these conclusions, Zwicky inferred some unseen matter provided the mass and associated gravitation attraction to hold the cluster together. Zwicky's estimates were off by more than an order of magnitude, mainly due to an obsolete value of the Hubble constant; the same calculation today shows a smaller fraction, using greater values for luminous mass. Nonetheless, Zwicky did correctly conclude from his calculation that the bulk of the matter was dark.

Further indications of mass-to-light ratio anomalies came from measurements of galaxy rotation curves. In 1939, Horace W. Babcock reported the rotation curve for the Andromeda nebula (known now as the Andromeda Galaxy), which suggested the mass-to-luminosity ratio increases radially. He attributed it to either light absorption within the galaxy or modified dynamics in the outer portions of the spiral and not to the missing matter he had uncovered. Following Babcock's 1939 report of unexpectedly rapid rotation in the outskirts of the Andromeda galaxy and a mass-to-light ratio of 50; in 1940 Jan Oort discovered and wrote about the large non-visible halo of NGC 3115.

1960s
Early radio astronomy observations, performed by Seth Shostak, later SETI Institute Senior Astronomer, showed a half-dozen galaxies spun too fast in their outer regions, pointing to the existence of dark matter as a means of creating the gravitational pull needed to keep the stars in their orbits.

1970s
Vera Rubin, Kent Ford, and Ken Freeman's work in the 1960s and 1970s provided further strong evidence, also using galaxy rotation curves. Rubin and Ford worked with a new spectrograph to measure the velocity curve of edge-on spiral galaxies with greater accuracy. This result was confirmed in 1978. An influential paper presented Rubin and Ford's results in 1980. They showed most galaxies must contain about six times as much dark as visible mass; thus, by around 1980 the apparent need for dark matter was widely recognized as a major unsolved problem in astronomy.

At the same time, Rubin and Ford were exploring optical rotation curves, radio astronomers were making use of new radio telescopes to map the 21 cm line of atomic hydrogen in nearby galaxies. The radial distribution of interstellar atomic hydrogen (H$26.8⁄4.9 + 26.8$) often extends to much greater galactic distances than can be observed as collective starlight, expanding the sampled distances for rotation curves – and thus of the total mass distribution – to a new dynamical regime. Early mapping of Andromeda with the 300 foot telescope at Green Bank and the 250 foot dish at Jodrell Bank already showed the H$$R = 4$$ rotation curve did not trace the expected Keplerian decline. As more sensitive receivers became available, Roberts & Whitehurst (1975) were able to trace the rotational velocity of Andromeda to 30 kpc, much beyond the optical measurements. Illustrating the advantage of tracing the gas disk at large radii; that paper's Figure 16 combines the optical data (the cluster of points at radii of less than 15 kpc with a single point further out) with the H$$R = 122$$ data between 20 and 30 kpc, exhibiting the flatness of the outer galaxy rotation curve; the solid curve peaking at the center is the optical surface density, while the other curve shows the cumulative mass, still rising linearly at the outermost measurement. In parallel, the use of interferometric arrays for extragalactic H$$I$$ spectroscopy was being developed. Rogstad & Shostak (1972) published H$$I$$ rotation curves of five spirals mapped with the Owens Valley interferometer; the rotation curves of all five were very flat, suggesting very large values of mass-to-light ratio in the outer parts of their extended H$$I$$ disks.

1980s
A stream of observations in the 1980s supported the presence of dark matter, including gravitational lensing of background objects by galaxy clusters, the temperature distribution of hot gas in galaxies and clusters, and the pattern of anisotropies in the cosmic microwave background. According to consensus among cosmologists, dark matter is composed primarily of a not-yet-characterized type of subatomic particle. The search for this particle, by a variety of means, is one of the major efforts in particle physics.

Technical definition
In standard cosmological calculations, "matter" means any constituent of the universe whose energy density scales with the inverse cube of the scale factor, i.e., $I$. This is in contrast to "radiation", which scales as the inverse fourth power of the scale factor $I$, and a cosmological constant, which does not change with respect to $$I$$ ($ρ ∝ a−3$). The different scaling factors for matter and radiation are a consequence of radiation redshift: For example, after gradually doubling the diameter of the observable Universe via cosmic expansion of General Relativity, the scale, $a$, has doubled. The energy of the cosmic microwave background radiation has been halved (because the wavelength of each photon has doubled); the energy of ultra-relativistic particles, such as early-era standard-model neutrinos, is similarly halved. The cosmological constant, as an intrinsic property of space, has a constant energy density regardless of the volume under consideration.

In principle, "dark matter" means all components of the universe which are not visible but still obey $ρ ∝ a−4$. In practice, the term "dark matter" is often used to mean only the non-baryonic component of dark matter, i.e., excluding "missing baryons". Context will usually indicate which meaning is intended.

Galaxy rotation curves
The arms of spiral galaxies rotate around the galactic center. The luminous mass density of a spiral galaxy decreases as one goes from the center to the outskirts. If luminous mass were all the matter, then we can model the galaxy as a point mass in the centre and test masses orbiting around it, similar to the Solar System. From Kepler's Third Law, it is expected that the rotation velocities will decrease with distance from the center, similar to the Solar System. This is not observed. Instead, the galaxy rotation curve remains flat as distance from the center increases.

If Kepler's laws are correct, then the obvious way to resolve this discrepancy is to conclude the mass distribution in spiral galaxies is not similar to that of the Solar System. In particular, there is a lot of non-luminous matter (dark matter) in the outskirts of the galaxy.

Velocity dispersions
Stars in bound systems must obey the virial theorem. The theorem, together with the measured velocity distribution, can be used to measure the mass distribution in a bound system, such as elliptical galaxies or globular clusters. With some exceptions, velocity dispersion estimates of elliptical galaxies do not match the predicted velocity dispersion from the observed mass distribution, even assuming complicated distributions of stellar orbits.

As with galaxy rotation curves, the obvious way to resolve the discrepancy is to postulate the existence of non-luminous matter.

Galaxy clusters
Galaxy clusters are particularly important for dark matter studies since their masses can be estimated in three independent ways:
 * From the scatter in radial velocities of the galaxies within clusters
 * From X-rays emitted by hot gas in the clusters. From the X-ray energy spectrum and flux, the gas temperature and density can be estimated, hence giving the pressure; assuming pressure and gravity balance determines the cluster's mass profile.
 * Gravitational lensing (usually of more distant galaxies) can measure cluster masses without relying on observations of dynamics (e.g., velocity).

Generally, these three methods are in reasonable agreement that dark matter outweighs visible matter by approximately 5 to 1.

Gravitational lensing
One of the consequences of general relativity is the gravitational lens. Gravitational lensing occurs when massive objects between a source of light and the observer act as a lens to bend light from this source. One example is a cluster of galaxies lying between a more distant source such as a quasar and an observer. The more massive an object, the more lensing is observed.

Strong lensing is the observed distortion of background galaxies into arcs when their light passes through such a gravitational lens. It has been observed around many distant clusters including Abell 1689. By measuring the distortion geometry, the mass of the intervening cluster can be obtained. In the dozens of cases where this has been done, the mass-to-light ratios obtained correspond to the dynamical dark matter measurements of clusters. Lensing can lead to multiple copies of an image. By analyzing the distribution of multiple image copies, scientists have been able to deduce and map the distribution of dark matter around the MACS J0416.1-2403 galaxy cluster.

Weak gravitational lensing investigates minute distortions of galaxies, using statistical analyses from vast galaxy surveys. By examining the apparent shear deformation of the adjacent background galaxies, the mean distribution of dark matter can be characterized. The mass-to-light ratios correspond to dark matter densities predicted by other large-scale structure measurements. Dark matter does not bend light itself; mass (in this case the mass of the dark matter) bends spacetime. Light follows the curvature of spacetime, resulting in the lensing effect.

In May 2021, a new detailed dark matter map was revealed by the Dark Energy Survey Collaboration. In addition, the map revealed previously undiscovered filamentary structures connecting galaxies, by using a machine learning method.

An April 2023 study in Nature Astronomy examined the inferred distribution of the dark matter responsible for the lensing of the elliptical galaxy HS 0810+2554, and found tentative evidence of interference patterns within the dark matter. The observation of interference patterns is incompatible with WIMPs, but would be compatible with simulations involving 10−22 eV axions. While acknowledging the need to corroborate the findings by examining other astrophysical lenses, the authors argued that "The ability of (axion-based dark matter) to resolve lensing anomalies even in demanding cases such as HS 0810+2554, together with its success in reproducing other astrophysical observations, tilt the balance toward new physics invoking axions."

Cosmic microwave background
Although both dark matter and ordinary matter are matter, they do not behave in the same way. In particular, in the early universe, ordinary matter was ionized and interacted strongly with radiation via Thomson scattering. Dark matter does not interact directly with radiation, but it does affect the cosmic microwave background (CMB) by its gravitational potential (mainly on large scales) and by its effects on the density and velocity of ordinary matter. Ordinary and dark matter perturbations, therefore, evolve differently with time and leave different imprints on the CMB.

The cosmic microwave background is very close to a perfect blackbody but contains very small temperature anisotropies of a few parts in 100,000. A sky map of anisotropies can be decomposed into an angular power spectrum, which is observed to contain a series of acoustic peaks at near-equal spacing but different heights. The series of peaks can be predicted for any assumed set of cosmological parameters by modern computer codes such as CMBFAST and CAMB, and matching theory to data, therefore, constrains cosmological parameters.

The first peak mostly shows that the universe is close to spatially flat. The second peak constrains the cosmological density of baryons. The third peak pins down the cosmological density of dark matter.

The CMB anisotropy was first discovered by COBE in 1992, though this had too coarse resolution to detect the acoustic peaks. After the discovery of the first acoustic peak by the balloon-borne BOOMERanG experiment in 2000, the power spectrum was precisely observed by WMAP in 2003–2012, and even more precisely by the Planck spacecraft in 2013–2015. The results support the Lambda-CDM model.

The observed CMB angular power spectrum provides powerful evidence in support of dark matter, as its precise structure is well fitted by the lambda-CDM model, but difficult to reproduce with any competing model such as modified Newtonian dynamics (MOND).

Structure formation
Structure formation refers to the period after the Big Bang when density perturbations collapsed to form stars, galaxies, and clusters. Prior to structure formation, the Friedmann solutions to general relativity describe a homogeneous universe. Later, small anisotropies gradually grew and condensed the homogeneous universe into stars, galaxies and larger structures. Ordinary matter is affected by radiation, which is the dominant element of the universe at very early times. As a result, its density perturbations are washed out and unable to condense into structure. If there were only ordinary matter in the universe, there would not have been enough time for density perturbations to grow into the galaxies and clusters currently seen.

Dark matter provides a solution to this problem because it is unaffected by radiation. Therefore, its density perturbations can grow first. The resulting gravitational potential acts as an attractive potential well for ordinary matter collapsing later, speeding up the structure formation process.

Bullet Cluster
The Bullet Cluster, the result of a recent collision of two galaxy clusters, provides model-independent observational evidence for Dark matter. Alternatives like modified gravity theories have a difficult time explaining this system because its apparent center of mass is far displaced from the baryonic center of mass.

Type Ia supernova distance measurements
Type Ia supernovae can be used as standard candles to measure extragalactic distances, which can in turn be used to measure how fast the universe has expanded in the past. Data indicates the universe is expanding at an accelerating rate, the cause of which is usually ascribed to dark energy. Since observations indicate the universe is almost flat, it is expected the total energy density of everything in the universe should sum to 1 (Ωtot ≈ 1). The measured dark energy density is ΩΛ ≈ 0.690; the observed ordinary (baryonic) matter energy density is Ωb ≈ 0.0482 and the energy density of radiation is negligible. This leaves a missing Ωdm ≈ 0.258 which nonetheless behaves like matter (see technical definition section above) – dark matter.

Sky surveys and baryon acoustic oscillations
Baryon acoustic oscillations (BAO) are fluctuations in the density of the visible baryonic matter (normal matter) of the universe on large scales. These are predicted to arise in the Lambda-CDM model due to acoustic oscillations in the photon–baryon fluid of the early universe and can be observed in the cosmic microwave background angular power spectrum. BAOs set up a preferred length scale for baryons. As the dark matter and baryons clumped together after recombination, the effect is much weaker in the galaxy distribution in the nearby universe, but is detectable as a subtle (≈1 percent) preference for pairs of galaxies to be separated by 147 Mpc, compared to those separated by 130–160 Mpc. This feature was predicted theoretically in the 1990s and then discovered in 2005, in two large galaxy redshift surveys, the Sloan Digital Sky Survey and the 2dF Galaxy Redshift Survey. Combining the CMB observations with BAO measurements from galaxy redshift surveys provides a precise estimate of the Hubble constant and the average matter density in the Universe. The results support the Lambda-CDM model.

Redshift-space distortions
Large galaxy redshift surveys may be used to make a three-dimensional map of the galaxy distribution. These maps are slightly distorted because distances are estimated from observed redshifts; the redshift contains a contribution from the galaxy's so-called peculiar velocity in addition to the dominant Hubble expansion term. On average, superclusters are expanding more slowly than the cosmic mean due to their gravity, while voids are expanding faster than average. In a redshift map, galaxies in front of a supercluster have excess radial velocities towards it and have redshifts slightly higher than their distance would imply, while galaxies behind the supercluster have redshifts slightly low for their distance. This effect causes superclusters to appear squashed in the radial direction, and likewise voids are stretched. Their angular positions are unaffected. This effect is not detectable for any one structure since the true shape is not known, but can be measured by averaging over many structures. It was predicted quantitatively by Nick Kaiser in 1987, and first decisively measured in 2001 by the 2dF Galaxy Redshift Survey. Results are in agreement with the lambda-CDM model.

Lyman-alpha forest
In astronomical spectroscopy, the Lyman-alpha forest is the sum of the absorption lines arising from the Lyman-alpha transition of neutral hydrogen in the spectra of distant galaxies and quasars. Lyman-alpha forest observations can also constrain cosmological models. These constraints agree with those obtained from WMAP data.

Composition
The identity of dark matter is unknown, but there are many hypotheses about what dark matter could consist of, as set out in the table below.

Baryonic matter
Dark matter can refer to any substance which interacts predominantly via gravity with visible matter (e.g., stars and planets). Hence in principle it need not be composed of a new type of fundamental particle but could, at least in part, be made up of standard baryonic matter, such as protons or neutrons. Most of the ordinary matter familiar to astronomers, including planets, brown dwarfs, red dwarfs, visible stars, white dwarfs, neutron stars, and black holes, fall into this category. Solitary black holes, neutron stars, burnt-out dwarfs, and other massive objects that are hard to detect are collectively known as MACHOs; some scientists initially hoped that baryonic MACHOs could account for and explain all the dark matter.

However, multiple lines of evidence suggest the majority of dark matter is not baryonic:
 * Sufficient diffuse, baryonic gas or dust would be visible when backlit by stars.
 * The theory of Big Bang nucleosynthesis predicts the observed abundance of the chemical elements. If there are more baryons, then there should also be more helium, lithium and heavier elements synthesized during the Big Bang. Agreement with observed abundances requires that baryonic matter makes up between 4–5% of the universe's critical density. In contrast, large-scale structure and other observations indicate that the total matter density is about 30% of the critical density.
 * Astronomical searches for gravitational microlensing in the Milky Way found at most only a small fraction of the dark matter may be in dark, compact, conventional objects (MACHOs, etc.); the excluded range of object masses is from half the Earth's mass up to 30 solar masses, which covers nearly all the plausible candidates.
 * Detailed analysis of the small irregularities (anisotropies) in the cosmic microwave background. Observations by WMAP and Planck indicate that around five-sixths of the total matter is in a form that interacts significantly with ordinary matter or photons only through gravitational effects.

Non-baryonic matter
There are two main candidates for non-baryonic dark matter: hypothetical particles such as axions, sterile neutrinos, weakly interacting massive particle (WIMPs), supersymmetric particles, atomic dark matter, or geons; and primordial black holes. Once a black hole ingests either kind of matter, baryonic or not, the distinction is lost.

Unlike baryonic matter, nonbaryonic particles do not contribute to the formation of the elements in the early universe (Big Bang nucleosynthesis) and so its presence is revealed only via its gravitational effects, or weak lensing. In addition, if the particles of which it is composed are supersymmetric, they can undergo annihilation interactions with themselves, possibly resulting in observable by-products such as gamma rays and neutrinos (indirect detection).

In 2015, the idea that dense dark matter was composed of primordial black holes made a comeback following results of gravitational wave measurements which detected the merger of intermediate-mass black holes. Black holes with about 30 solar masses are not predicted to form by either stellar collapse (typically less than 15 solar masses) or by the merger of black holes in galactic centers (millions or billions of solar masses). It was proposed that the intermediate-mass black holes causing the detected merger formed in the hot dense early phase of the universe due to denser regions collapsing. A later survey of about a thousand supernovae detected no gravitational lensing events, when about eight would be expected if intermediate-mass primordial black holes above a certain mass range accounted for over 60% of dark matter. However, that study assumed a monochromatic distribution to represent the LIGO/Virgo mass range, which is inapplicable to the broadly platykurtic mass distribution suggested by subsequent James Webb Space Telescope observations.

The possibility that atom-sized primordial black holes account for a significant fraction of dark matter was ruled out by measurements of positron and electron fluxes outside the Sun's heliosphere by the Voyager 1 spacecraft. Tiny black holes are theorized to emit Hawking radiation. However the detected fluxes were too low and did not have the expected energy spectrum, suggesting that tiny primordial black holes are not widespread enough to account for dark matter. Nonetheless, research and theories proposing dense dark matter accounts for dark matter continue as of 2018, including approaches to dark matter cooling, and the question remains unsettled. In 2019, the lack of microlensing effects in the observation of Andromeda suggests that tiny black holes do not exist.

However, there still exists a largely unconstrained mass range smaller than that which can be limited by optical microlensing observations, where primordial black holes may account for all dark matter.

Free streaming length
Dark matter can be divided into cold, warm, and hot categories. These categories refer to velocity rather than an actual temperature, indicating how far corresponding objects moved due to random motions in the early universe, before they slowed due to cosmic expansion – this is an important distance called the free streaming length (FSL). Primordial density fluctuations smaller than this length get washed out as particles spread from overdense to underdense regions, while larger fluctuations are unaffected; therefore this length sets a minimum scale for later structure formation.

The categories are set with respect to the size of a protogalaxy (an object that later evolves into a dwarf galaxy): Dark matter particles are classified as cold, warm, or hot according to their FSL; much smaller (cold), similar to (warm), or much larger (hot) than a protogalaxy. Mixtures of the above are also possible: a theory of mixed dark matter was popular in the mid-1990s, but was rejected following the discovery of dark energy.

Cold dark matter leads to a bottom-up formation of structure with galaxies forming first and galaxy clusters at a latter stage, while hot dark matter would result in a top-down formation scenario with large matter aggregations forming early, later fragmenting into separate galaxies; the latter is excluded by high-redshift galaxy observations.

Fluctuation spectrum effects
These categories also correspond to fluctuation spectrum effects and the interval following the Big Bang at which each type became non-relativistic. Davis et al. wrote in 1985: "Candidate particles can be grouped into three categories on the basis of their effect on the fluctuation spectrum (Bond et al. 1983). If the dark matter is composed of abundant light particles which remain relativistic until shortly before recombination, then it may be termed 'hot'. The best candidate for hot dark matter is a neutrino ... A second possibility is for the dark matter particles to interact more weakly than neutrinos, to be less abundant, and to have a mass of order 1 keV. Such particles are termed 'warm dark matter', because they have lower thermal velocities than massive neutrinos ... there are at present few candidate particles which fit this description. Gravitinos and photinos have been suggested (Pagels and Primack 1982; Bond, Szalay and Turner 1982) ... Any particles which became nonrelativistic very early, and so were able to diffuse a negligible distance, are termed 'cold' dark matter (CDM). There are many candidates for CDM including supersymmetric particles. — Davis, Efstathiou, Frenk, & White (1985)"

Alternative definitions
Another approximate dividing line is warm dark matter became non-relativistic when the universe was approximately 1 year old and 1 millionth of its present size and in the radiation-dominated era (photons and neutrinos), with a photon temperature 2.7 million Kelvins. Standard physical cosmology gives the particle horizon size as $$2 c t$$ (speed of light multiplied by time) in the radiation-dominated era, thus 2 light-years. A region of this size would expand to 2 million light-years today (absent structure formation). The actual FSL is approximately 5 times the above length, since it continues to grow slowly as particle velocities decrease inversely with the scale factor after they become non-relativistic. In this example the FSL would correspond to 10 million light-years (or 3 megaparsecs) today, around the size containing an average large galaxy.

The 2.7 million Kelvin photon temperature gives a typical photon energy of 250 electronvolt, thereby setting a typical mass scale for warm dark matter: particles much more massive than this, such as GeV–TeV mass WIMPs, would become non-relativistic much earlier than one year after the Big Bang and thus have FSLs much smaller than a protogalaxy, making them cold. Conversely, much lighter particles, such as neutrinos with masses of only a few electronvolt, have FSLs much larger than a protogalaxy, thus qualifying them as hot.

Cold dark matter
Cold dark matter offers the simplest explanation for most cosmological observations. It is dark matter composed of constituents with an FSL much smaller than a protogalaxy. This is the focus for dark matter research, as hot dark matter does not seem capable of supporting galaxy or galaxy cluster formation, and most particle candidates slowed early.

The constituents of cold dark matter are unknown. Possibilities range from large objects like MACHOs (such as black holes and Preon stars ) or RAMBOs (such as clusters of brown dwarfs), to new particles such as WIMPs and axions.

The 1997 DAMA/NaI experiment and its successor DAMA/LIBRA in 2013, claimed to directly detect dark matter particles passing through the Earth, but many researchers remain skeptical, as negative results from similar experiments seem incompatible with the DAMA results.

Many supersymmetric models offer dark matter candidates in the form of the WIMPy Lightest Supersymmetric Particle (LSP). Separately, heavy sterile neutrinos exist in non-supersymmetric extensions to the standard model which explain the small neutrino mass through the seesaw mechanism.

Warm dark matter
Warm dark matter comprises particles with an FSL comparable to the size of a protogalaxy. Predictions based on warm dark matter are similar to those for cold dark matter on large scales, but with less small-scale density perturbations. This reduces the predicted abundance of dwarf galaxies and may lead to lower density of dark matter in the central parts of large galaxies. Some researchers consider this a better fit to observations. A challenge for this model is the lack of particle candidates with the required mass ≈ 300 eV to 3000 eV.

No known particles can be categorized as warm dark matter. A postulated candidate is the sterile neutrino: a heavier, slower form of neutrino that does not interact through the weak force, unlike other neutrinos. Some modified gravity theories, such as scalar–tensor–vector gravity, require "warm" dark matter to make their equations work.

Hot dark matter
Hot dark matter consists of particles whose FSL is much larger than the size of a protogalaxy. The neutrino qualifies as such a particle. They were discovered independently, long before the hunt for dark matter: they were postulated in 1930, and detected in 1956. Neutrinos' mass is less than 10$a$ that of an electron. Neutrinos interact with normal matter only via gravity and the weak force, making them difficult to detect (the weak force only works over a small distance, thus a neutrino triggers a weak force event only if it hits a nucleus head-on). This makes them "weakly interacting slender particles" (WISPs), as opposed to WIMPs.

The three known flavours of neutrinos are the electron, muon, and tau. Neutrinos oscillate among the flavours as they move. It is hard to determine an exact upper bound on the collective average mass of the three neutrinos. For example, if the average neutrino mass were over 50 eV/c$−6$ (less than 10$2$ of the mass of an electron), the universe would collapse. CMB data and other methods indicate that their average mass probably does not exceed 0.3 eV/c$−5$. Thus, observed neutrinos cannot explain dark matter.

Because galaxy-size density fluctuations get washed out by free-streaming, hot dark matter implies the first objects that can form are huge supercluster-size pancakes, which then fragment into galaxies. Deep-field observations show instead that galaxies formed first, followed by clusters and superclusters as galaxies clump together.

Dark matter aggregation and dense dark matter objects
If dark matter is composed of weakly interacting particles, then an obvious question is whether it can form objects equivalent to planets, stars, or black holes. Historically, the answer has been it cannot, because of two factors:
 * It lacks an efficient means to lose energy
 * Ordinary matter forms dense objects because it has numerous ways to lose energy. Losing energy would be essential for object formation, because a particle that gains energy during compaction or falling "inward" under gravity, and cannot lose it any other way, will heat up and increase velocity and momentum. Dark matter appears to lack a means to lose energy, simply because it is not capable of interacting strongly in other ways except through gravity. The virial theorem suggests that such a particle would not stay bound to the gradually forming object – as the object began to form and compact, the dark matter particles within it would speed up and tend to escape.

 * It lacks a diversity of interactions needed to form structures
 * Ordinary matter interacts in many different ways, which allows the matter to form more complex structures. For example, stars form through gravity, but the particles within them interact and can emit energy in the form of neutrinos and electromagnetic radiation through fusion when they become energetic enough. Protons and neutrons can bind via the strong interaction and then form atoms with electrons largely through electromagnetic interaction. There is no evidence that dark matter is capable of such a wide variety of interactions, since it seems to only interact through gravity (and possibly through some means no stronger than the weak interaction, although until dark matter is better understood, this is only speculation).

However, there are theories of atomic dark matter similar to normal matter that overcome these problems.

Detection of dark matter particles
If dark matter is made up of subatomic particles, then millions, possibly billions, of such particles must pass through every square centimeter of the Earth each second. Many experiments aim to test this hypothesis. Although WIMPs have been the main search candidates, axions have drawn renewed attention, with the Axion Dark Matter Experiment (ADMX) searches for axions and many more planned in the future. Another candidate is heavy hidden sector particles which only interact with ordinary matter via gravity.

These experiments can be divided into two classes: direct detection experiments, which search for the scattering of dark matter particles off atomic nuclei within a detector; and indirect detection, which look for the products of dark matter particle annihilations or decays.

Direct detection
Direct detection experiments aim to observe low-energy recoils (typically a few keVs) of nuclei induced by interactions with particles of dark matter, which (in theory) are passing through the Earth. After such a recoil, the nucleus will emit energy in the form of scintillation light or phonons as they pass through sensitive detection apparatus. To do so effectively, it is crucial to maintain an extremely low background, which is the reason why such experiments typically operate deep underground, where interference from cosmic rays is minimized. Examples of underground laboratories with direct detection experiments include the Stawell mine, the Soudan mine, the SNOLAB underground laboratory at Sudbury, the Gran Sasso National Laboratory, the Canfranc Underground Laboratory, the Boulby Underground Laboratory, the Deep Underground Science and Engineering Laboratory and the China Jinping Underground Laboratory.

These experiments mostly use either cryogenic or noble liquid detector technologies. Cryogenic detectors operating at temperatures below 100 mK, detect the heat produced when a particle hits an atom in a crystal absorber such as germanium. Noble liquid detectors detect scintillation produced by a particle collision in liquid xenon or argon. Cryogenic detector experiments include such projects as CDMS, CRESST, EDELWEISS, and EURECA, while noble liquid experiments include LZ, XENON, DEAP, ArDM, WARP, DarkSide, PandaX, and LUX, the Large Underground Xenon experiment. Both of these techniques focus strongly on their ability to distinguish background particles (which predominantly scatter off electrons) from dark matter particles (that scatter off nuclei). Other experiments include SIMPLE and PICASSO, which use alternative methods in their attempts to detect dark matter.

Currently there has been no well-established claim of dark matter detection from a direct detection experiment, leading instead to strong upper limits on the mass and interaction cross section with nucleons of such dark matter particles. The DAMA/NaI and more recent DAMA/LIBRA experimental collaborations have detected an annual modulation in the rate of events in their detectors, which they claim is due to dark matter. This results from the expectation that as the Earth orbits the Sun, the velocity of the detector relative to the dark matter halo will vary by a small amount. This claim is so far unconfirmed and in contradiction with negative results from other experiments such as LUX, SuperCDMS and XENON100.

A special case of direct detection experiments covers those with directional sensitivity. This is a search strategy based on the motion of the Solar System around the Galactic Center. A low-pressure time projection chamber makes it possible to access information on recoiling tracks and constrain WIMP-nucleus kinematics. WIMPs coming from the direction in which the Sun travels (approximately towards Cygnus) may then be separated from background, which should be isotropic. Directional dark matter experiments include DMTPC, DRIFT, Newage and MIMAC.

Indirect detection
Indirect detection experiments search for the products of the self-annihilation or decay of dark matter particles in outer space. For example, in regions of high dark matter density (e.g., the centre of our galaxy) two dark matter particles could annihilate to produce gamma rays or Standard Model particle–antiparticle pairs. Alternatively, if a dark matter particle is unstable, it could decay into Standard Model (or other) particles. These processes could be detected indirectly through an excess of gamma rays, antiprotons or positrons emanating from high density regions in our galaxy or others. A major difficulty inherent in such searches is that various astrophysical sources can mimic the signal expected from dark matter, and so multiple signals are likely required for a conclusive discovery.

A few of the dark matter particles passing through the Sun or Earth may scatter off atoms and lose energy. Thus dark matter may accumulate at the center of these bodies, increasing the chance of collision/annihilation. This could produce a distinctive signal in the form of high-energy neutrinos. Such a signal would be strong indirect proof of WIMP dark matter. High-energy neutrino telescopes such as AMANDA, IceCube and ANTARES are searching for this signal. The detection by LIGO in September 2015 of gravitational waves opens the possibility of observing dark matter in a new way, particularly if it is in the form of primordial black holes.

Many experimental searches have been undertaken to look for such emission from dark matter annihilation or decay, examples of which follow.

The Energetic Gamma Ray Experiment Telescope observed more gamma rays in 2008 than expected from the Milky Way, but scientists concluded this was most likely due to incorrect estimation of the telescope's sensitivity.

The Fermi Gamma-ray Space Telescope is searching for similar gamma rays. In 2009, an as yet unexplained surplus of gamma rays from the Milky Way's galactic center was found in Fermi data. This Galactic Center GeV excess might be due to dark matter annihilation or to a population of pulsars. In April 2012, an analysis of previously available data from Fermi's Large Area Telescope instrument produced statistical evidence of a 130 GeV signal in the gamma radiation coming from the center of the Milky Way. WIMP annihilation was seen as the most probable explanation.

At higher energies, ground-based gamma-ray telescopes have set limits on the annihilation of dark matter in dwarf spheroidal galaxies and in clusters of galaxies.

The PAMELA experiment (launched in 2006) detected excess positrons. They could be from dark matter annihilation or from pulsars. No excess antiprotons were observed.

In 2013, results from the Alpha Magnetic Spectrometer on the International Space Station indicated excess high-energy cosmic rays which could be due to dark matter annihilation.

Collider searches for dark matter
An alternative approach to the detection of dark matter particles in nature is to produce them in a laboratory. Experiments with the Large Hadron Collider (LHC) may be able to detect dark matter particles produced in collisions of the LHC proton beams. Because a dark matter particle should have negligible interactions with normal visible matter, it may be detected indirectly as (large amounts of) missing energy and momentum that escape the detectors, provided other (non-negligible) collision products are detected. Constraints on dark matter also exist from the LEP experiment using a similar principle, but probing the interaction of dark matter particles with electrons rather than quarks. Any discovery from collider searches must be corroborated by discoveries in the indirect or direct detection sectors to prove that the particle discovered is, in fact, dark matter.

Alternative hypotheses
Because dark matter has not yet been identified, many other hypotheses have emerged aiming to explain the same observational phenomena without introducing a new unknown type of matter. The theory underpinning most observational evidence for dark matter, general relativity, is well-tested on solar system scales, but its validity on galactic or cosmological scales has not been well proven. A suitable modification to general relativity can in principle conceivably eliminate the need for dark matter. The best-known theories of this class are MOND and its relativistic generalization tensor–vector–scalar gravity (TeVeS), f(R) gravity, negative mass, dark fluid, and entropic gravity. Alternative theories abound.

Primordial black holes are considered candidates for components of dark matter. Early constraints on primordial black holes as dark matter usually assumed most black holes would have similar or identical ("monochromatic") mass, which was disproven by LIGO/Virgo results. In 2024, a review by Bernard Carr and colleagues concluded that primordial black holes forming in the quantum chromodynamics epoch prior to 10–5 seconds after the Big Bang can explain most observations attributed to dark matter. Such black hole formation would result in an extended mass distribution today, "with a number of distinct bumps, the most prominent one being at around one solar mass."

A problem with alternative hypotheses is that observational evidence for dark matter comes from so many independent approaches (see the "observational evidence" section above). Explaining any individual observation is possible but explaining all of them in the absence of dark matter is very difficult. Nonetheless, there have been some scattered successes for alternative hypotheses, such as a 2016 test of gravitational lensing in entropic gravity  and a 2020 measurement of a unique MOND effect.

The prevailing opinion among most astrophysicists is that while modifications to general relativity can conceivably explain part of the observational evidence, there is probably enough data to conclude there must be some form of dark matter present in the universe.

In popular culture
Dark matter regularly appears as a topic in hybrid periodicals that cover both factual scientific topics and science fiction, and dark matter itself has been referred to as "the stuff of science fiction".

Mention of dark matter is made in works of fiction. In such cases, it is usually attributed extraordinary physical or magical properties, thus becoming inconsistent with the hypothesized properties of dark matter in physics and cosmology. For example:
 * Dark matter serves as a plot device in the X-Files episode "Soft Light."
 * A dark-matter-inspired substance known as "Dust" features prominently in Philip Pullman's His Dark Materials trilogy.
 * Beings made of dark matter are antagonists in Stephen Baxter's Xeelee Sequence.

More broadly, the phrase "dark matter" is used metaphorically in fiction to evoke the unseen or invisible.

title: Dark matter