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Diacritic

A diacritic (also diacritical mark, diacritical point, diacritical sign, or accent) is a glyph added to a letter or to a basic glyph. The term derives from the Ancient Greek (diakritikós, "distinguishing"), from διακρίνω (diakrínō, "to distinguish"). The word diacritic is a noun, though it is sometimes used in an attributive sense, whereas diacritical is only an adjective. Some diacritics, such as the acute $⟨ó⟩$, grave $⟨ò⟩$, and circumflex $⟨ô⟩$ (all shown above an 'o'), are often called accents. Diacritics may appear above or below a letter or in some other position such as within the letter or between two letters.

The main use of diacritics in Latin script is to change the sound-values of the letters to which they are added. Historically, English has used the diaeresis diacritic to indicate the correct pronunciation of ambiguous words, such as "coöperate", without which the  letter sequence could be misinterpreted to be pronounced. Other examples are the acute and grave accents, which can indicate that a vowel is to be pronounced differently than is normal in that position, for example not reduced to /ə/ or silent as in the case of the two uses of the letter e in the noun résumé (as opposed to the verb resume) and the help sometimes provided in the pronunciation of some words such as doggèd, learnèd, blessèd, and especially words pronounced differently than normal in poetry (for example movèd, breathèd).

Most other words with diacritics in English are borrowings from languages such as French to better preserve the spelling, such as the diaeresis on naïve and Noël, the acute from café, the circumflex in the word crêpe, and the cedille in façade. All these diacritics, however, are frequently omitted in writing, and English is the only major modern European language that does not have diacritics in common usage.

In Latin-script alphabets in other languages, diacritics may distinguish between homonyms, such as the French là ("there") versus la ("the"), which are both pronounced. In Gaelic type, a dot over a consonant indicates lenition of the consonant in question. In other writing systems, diacritics may perform other functions. Vowel pointing systems, namely the Arabic harakat and the Hebrew niqqud systems, indicate vowels that are not conveyed by the basic alphabet. The Indic virama (  ्  etc.) and the Arabic sukūn (  ـْـ  ) mark the absence of vowels. Cantillation marks indicate prosody. Other uses include the Early Cyrillic titlo stroke (  ◌҃  ) and the Hebrew gershayim (  ״  ), which, respectively, mark abbreviations or acronyms, and Greek diacritical marks, which showed that letters of the alphabet were being used as numerals. In Vietnamese and the Hanyu Pinyin official romanization system for Mandarin in China, diacritics are used to mark the tones of the syllables in which the marked vowels occur.

In orthography and collation, a letter modified by a diacritic may be treated either as a new, distinct letter or as a letter–diacritic combination. This varies from language to language and may vary from case to case within a language.

In some cases, letters are used as "in-line diacritics", with the same function as ancillary glyphs, in that they modify the sound of the letter preceding them, as in the case of the "h" in the English pronunciation of "sh" and "th". Such letter combinations are sometimes even collated as a single distinct letter. For example, the spelling sch was traditionally often treated as a separate letter in German. Words with that spelling were listed after all other words spelled with s in card catalogs in the Vienna public libraries, for example (before digitization).

Types
Among the types of diacritic used in alphabets based on the Latin script are:
 * accents (so called because the acute, grave, and circumflex were originally used to indicate different types of pitch accents in the polytonic transcription of Greek)

 * ◌́ – acute (apex); for example ó
 * ◌̀ – grave; for example ò
 * ◌̂ – circumflex; for example ô
 * ◌̌ – caron, wedge; for example ǒ
 * ◌̋ – double acute; for example ő
 * ◌̏ – double grave; for example ȍ
 * ◌̃ – tilde; for example õ
 * one dot
 * ◌̇ – an overdot is used in many orthographies and transcriptions; for example ȯ
 * ◌̣ – an underdot is also used in many orthographies and transcriptions; for example ọ
 * ◌·◌ – an interpunct is used in the Catalan ela geminada (l·l)
 * ◌͘ – a dot above right is used in Pe̍h-ōe-jī
 * tittle, the superscript dot of the modern lowercase Latin i and j
 * two dots:
 * two overdots (◌̈ ) are used for umlaut, diaeresis and others; (for example ö)
 * two underdots ( ◌̤ ) are used in the International Phonetic Alphabet (IPA) and the ALA-LC romanization system
 * ◌ː – triangular colon, used in the IPA to mark long vowels (the "dots" are triangular, not circular).
 * curves
 * ◌̆ – breve; for example ŏ
 * ◌̑ – inverted breve; for example ȏ
 * ◌͗ – sicilicus, a palaeographic diacritic similar to a caron or breve
 * ◌̃ – tilde; for example õ
 * ◌҃ – titlo
 * vertical stroke
 * ◌̩ – a subscript vertical stroke is used in IPA to mark syllabicity and in Rheinische Dokumenta to mark a schwa
 * ◌̍ – a superscript vertical stroke is used in Pe̍h-ōe-jī
 * macron or horizontal line
 * ◌̄ – macron; for example ō
 * ◌̱ – underbar
 * overlays
 * ◌⃓ – vertical bar through the character
 * ◌̷ – slash through the character; for example ø
 * ◌̵ – crossbar through the character
 * ring
 * ◌̊ – overring: for example å
 * superscript curls
 * ◌̓ – apostrophe
 * ◌̒ – inverted apostrophe
 * ◌̔ – reversed apostrophe
 * ◌̉ – hook above (dấu hỏi)
 * ◌̛ – horn (dấu móc); for example ơ
 * subscript curls
 * ◌̦ – undercomma; for example ș
 * ◌̧ – cedilla; for example ç
 * ◌̡ ◌̢ – hook, left or right, sometimes superscript
 * ◌̨ – ogonek; for example ǫ
 * double marks (over or under two base characters)
 * ◌͝◌ – double breve
 * ◌͡◌ – tie bar or top ligature
 * ◌᷍◌ – double circumflex
 * ◌͞◌ – longum
 * ◌͠◌ – double tilde
 * double sub/superscript diacritics
 * ◌̧ ̧ – double cedilla
 * ◌̨ ̨ – double ogonek
 * ◌̈ ̈ – double diaeresis
 * ◌ͅͺ – double ypogegrammeni

The tilde, dot, comma, titlo, apostrophe, bar, and colon are sometimes diacritical marks, but also have other uses.

Not all diacritics occur adjacent to the letter they modify. In the Wali language of Ghana, for example, an apostrophe indicates a change of vowel quality, but occurs at the beginning of the word, as in the dialects ’Bulengee and ’Dolimi. Because of vowel harmony, all vowels in a word are affected, so the scope of the diacritic is the entire word. In abugida scripts, like those used to write Hindi and Thai, diacritics indicate vowels, and may occur above, below, before, after, or around the consonant letter they modify.

The tittle (dot) on the letter i or the letter j, of the Latin alphabet originated as a diacritic to clearly distinguish i from the minims (downstrokes) of adjacent letters. It first appeared in the 11th century in the sequence ii (as in ingeníí), then spread to i adjacent to m, n, u, and finally to all lowercase is. The j, originally a variant of i, inherited the tittle. The shape of the diacritic developed from initially resembling today's acute accent to a long flourish by the 15th century. With the advent of Roman type it was reduced to the round dot we have today.

Several languages of eastern Europe use diacritics on both consonants and vowels, whereas in western Europe digraphs are more often used to change consonant sounds. Most languages in Europe use diacritics on vowels, aside from English where there are typically none (with some exceptions).

Arabic

 * (ئ ؤ إ أ and stand alone ء) hamza: indicates a glottal stop.
 * (ــًــٍــٌـ) tanwīn (تنوين) symbols: Serve a grammatical role in Arabic. The sign ـً is most commonly written in combination with alif, e.g. ـًا.
 * (ــّـ) shadda: Gemination (doubling) of consonants.
 * (ٱ) waṣla: Comes most commonly at the beginning of a word. Indicates a type of hamza that is pronounced only when the letter is read at the beginning of the talk.
 * (آ) madda: A written replacement for a hamza that is followed by an alif, i.e. (ءا). Read as a glottal stop followed by a long, e.g. ءاداب، ءاية، قرءان، مرءاة are written out respectively as آداب، آية، قرآن، مرآة. This writing rule does not apply when the alif that follows a hamza is not a part of the stem of the word, e.g. نتوءات is not written out as نتوآت as the stem نتوء does not have an alif that follows its hamza.
 * (ــٰـ) superscript alif (also "short" or "dagger alif": A replacement for an original alif that is dropped in the writing out of some rare words, e.g. لاكن is not written out with the original alif found in the word pronunciation, instead it is written out as لٰكن.
 * ḥarakāt (In Arabic: حركات also called تشكيل tashkīl):
 * (ــَـ) fatḥa (a)
 * (ــِـ) kasra (i)
 * (ــُـ) ḍamma (u)
 * (ــْـ) sukūn (no vowel)
 * The ḥarakāt or vowel points serve two purposes:
 * They serve as a phonetic guide. They indicate the presence of short vowels (fatḥa, kasra, or ḍamma) or their absence (sukūn).
 * At the last letter of a word, the vowel point reflects the inflection case or conjugation mood.
 * For nouns, The ḍamma is for the nominative, fatḥa for the accusative, and kasra for the genitive.
 * For verbs, the ḍamma is for the imperfective, fatḥa for the perfective, and the sukūn is for verbs in the imperative or jussive moods.
 * Vowel points or tashkīl should not be confused with consonant points or iʿjam (إعجام) – one, two or three dots written above or below a consonant to distinguish between letters of the same or similar form.

Greek
These diacritics are used in addition to the acute, grave, and circumflex accents and the diaeresis:
 * ◌ͺ – iota subscript (ᾳ, εͅ, ῃ, ιͅ, οͅ, υͅ, ῳ)
 * ῾◌ – rough breathing (δασὺ πνεῦμα, spīritus asper): aspiration
 * ᾿◌ – smooth (or soft) breathing (ψιλὸν πνεῦμα, spīritus lēnis): lack of aspiration

Hebrew

 * Niqqud
 * ּ – Dagesh
 * ּ – Mappiq
 * ֿ – Rafe
 * ׁ – Shin dot (at top right corner)
 * ׂ – Sin dot (at top left corner)
 * ְ – Shva
 * ֻ – Kubutz
 * ֹ◌ – Holam
 * ָ – Kamatz
 * ַ – Patakh
 * ֶ – Segol
 * ֵ – Tzeire
 * ִ – Hiriq
 * Cantillation marks do not generally render correctly; refer to Hebrew cantillation for a complete table together with instructions for how to maximize the possibility of viewing them in a web browser
 * Other
 * ׳ – Geresh
 * ״ – Gershayim

Korean
The diacritics  〮 and 〯, known as Bangjeom (방점; 傍點), were used to mark pitch accents in Hangul for Middle Korean. They were written to the left of a syllable in vertical writing and above a syllable in horizontal writing.

Sanskrit and Indic
[[File:Devanagari matras.svg|thumb|center|upright=3.4|Devanagari scripts (from Brahmic family) compound letters, which are vowels combined with consonants, have diacritics. Here, क (k) is shown with vowel diacritics.

That is: ा, ि, े, ु, ौ ़, ः, etc.]]

Syriac

 * A dot above and a dot below a letter represent, transliterated as a or ă,
 * Two diagonally-placed dots above a letter represent, transliterated as ā or â or å,
 * Two horizontally-placed dots below a letter represent, transliterated as e or ĕ; often pronounced and transliterated as i in the East Syriac dialect,
 * Two diagonally-placed dots below a letter represent, transliterated as ē,
 * A dot underneath the Beth represent a soft sound, transliterated as v
 * A tilde (~) placed under Gamel represent a sound, transliterated as j
 * The letter Waw with a dot below it represents, transliterated as ū or u,
 * The letter Waw with a dot above it represents, transliterated as ō or o,
 * The letter Yōḏ with a dot beneath it represents, transliterated as ī or i,
 * A tilde (~) under Kaph represent a sound, transliterated as ch or č,
 * A semicircle under Peh represents an sound, transliterated as f or ph.

In addition to the above vowel marks, transliteration of Syriac sometimes includes ə, e̊ or superscript e (or often nothing at all) to represent an original Aramaic schwa that became lost later on at some point in the development of Syriac. Some transliteration schemes find its inclusion necessary for showing spirantization or for historical reasons.

Non-alphabetic scripts
Some non-alphabetic scripts also employ symbols that function essentially as diacritics.
 * Non-pure abjads (such as Hebrew and Arabic script) and abugidas use diacritics for denoting vowels. Hebrew and Arabic also indicate consonant doubling and change with diacritics; Hebrew and Devanagari use them for foreign sounds. Devanagari and related abugidas also use a diacritical mark called a virama to mark the absence of a vowel. In addition, Devanagari uses the moon-dot chandrabindu ( ँ ) for vowel nasalization.
 * Unified Canadian Aboriginal Syllabics use several types of diacritics, including the diacritics with alphabetic properties known as Medials and Finals. Although long vowels originally were indicated with a negative line through the Syllabic glyphs, making the glyph appear broken, in the modern forms, a dot above is used to indicate vowel length. In some of the styles, a ring above indicates a long vowel with a [j] off-glide. Another diacritic, the "inner ring" is placed at the glyph's head to modify [p] to [f] and [t] to [θ]. Medials such as the "w-dot" placed next to the Syllabics glyph indicates a [w] being placed between the syllable onset consonant and the nucleus vowel. Finals indicate the syllable coda consonant; some of the syllable coda consonants in word medial positions, such as with the "h-tick", indicate the fortification of the consonant in the syllable following it.
 * The Japanese hiragana and katakana syllabaries use the dakuten (◌゛) and handakuten (◌゜) (in Japanese: 濁点 and 半濁点) symbols, also known as nigori (濁 "muddying") or ten-ten (点々 "dot dot") and maru (丸 "circle"), to indicate voiced consonants or other phonetic changes.
 * Emoticons are commonly created with diacritic symbols, especially Japanese emoticons on popular imageboards.

Alphabetization or collation
Different languages use different rules to put diacritic characters in alphabetical order. French and Portuguese treat letters with diacritical marks the same as the underlying letter for purposes of ordering and dictionaries.

The Scandinavian languages and the Finnish language, by contrast, treat the characters with diacritics å, ä, and ö as distinct letters of the alphabet, and sort them after z. Usually ä (a-umlaut) and ö (o-umlaut) [used in Swedish and Finnish] are sorted as equivalent to æ (ash) and ø (o-slash) [used in Danish and Norwegian]. Also, aa, when used as an alternative spelling to å, is sorted as such. Other letters modified by diacritics are treated as variants of the underlying letter, with the exception that ü is frequently sorted as y.

Languages that treat accented letters as variants of the underlying letter usually alphabetize words with such symbols immediately after similar unmarked words. For instance, in German where two words differ only by an umlaut, the word without it is sorted first in German dictionaries (e.g. schon and then schön, or fallen and then fällen). However, when names are concerned (e.g. in phone books or in author catalogues in libraries), umlauts are often treated as combinations of the vowel with a suffixed e; Austrian phone books now treat characters with umlauts as separate letters (immediately following the underlying vowel).

In Spanish, the grapheme ñ is considered a new letter different from n and collated between n and o, as it denotes a different sound from that of a plain n. But the accented vowels á, é, í, ó, ú are not separated from the unaccented vowels a, e, i, o, u, as the acute accent in Spanish only modifies stress within the word or denotes a distinction between homonyms, and does not modify the sound of a letter.

For a comprehensive list of the collating orders in various languages, see Collating sequence.

Generation with computers
Modern computer technology was developed mostly in English-speaking countries, so data formats, keyboard layouts, etc. were developed with a bias favoring English, a language with an alphabet without diacritical marks. Efforts have been made to create internationalized domain names that further extend the English alphabet (e.g., "pokémon.com").

Depending on the keyboard layout, which differs amongst countries, it is more or less easy to enter letters with diacritics on computers and typewriters. Some have their own keys; some are created by first pressing the key with the diacritic mark followed by the letter to place it on. Such a key is sometimes referred to as a dead key, as it produces no output of its own but modifies the output of the key pressed after it.

In modern Microsoft Windows and Linux operating systems, the keyboard layouts US International and UK International feature dead keys that allow one to type Latin letters with the acute, grave, circumflex, diaeresis/umlaut, tilde, and cedilla found in Western European languages (specifically, those combinations found in the ISO Latin-1 character set) directly: +  gives ë,  +  gives õ, etc. On Apple Macintosh computers, there are keyboard shortcuts for the most common diacritics;  followed by a vowel places an acute accent,  followed by a vowel gives an umlaut,  gives a cedilla, etc. Diacritics can be composed in most X Window System keyboard layouts, as well as other operating systems, such as Microsoft Windows, using additional software.

On computers, the availability of code pages determines whether one can use certain diacritics. Unicode solves this problem by assigning every known character its own code; if this code is known, most modern computer systems provide a method to input it. With Unicode, it is also possible to combine diacritical marks with most characters. However, as of 2019, very few fonts include the necessary support to correctly render character-plus-diacritic(s) for the Latin, Cyrillic and some other alphabets (exceptions include Andika).

Languages with letters containing diacritics
The following languages have letters with diacritics that are orthographically distinct from those without diacritics.

Baltic

 * Latvian has the following letters: ā, ē, ī, ū, č, ģ, ķ, ļ, ņ, š, ž
 * Lithuanian. In general usage, where letters appear with the caron (č, š and ž), they are considered as separate letters from c, s or z and collated separately; letters with the ogonek (ą, ę, į and ų), the macron (ū) and the superdot (ė) are considered as separate letters as well, but not given a unique collation order.

Celtic

 * Welsh uses the circumflex, diaeresis, acute, and grave accents on its seven vowels a, e, i, o, u, w, y (hence the composites â, ê, î, ô, û, ŵ, ŷ, ä, ë, ï, ö, ü, ẅ, ÿ, á, é, í, ó, ú, ẃ, ý, à, è, ì, ò, ù, ẁ, ỳ). However all except the circumflex (which is used as a macron) are fairly rare.
 * Following spelling reforms since the 1970s, Scottish Gaelic uses graves only, which can be used on any vowel (à, è, ì, ò, ù). Formerly acute accents could be used on á, ó and é, which were used to indicate a specific vowel quality. With the elimination of these accents, the new orthography relies on the reader having prior knowledge of pronunciation of a given word.
 * Manx uses the single diacritic ç combined with h to give the digraph $\langleçh\rangle$ (pronounced ) to mark the distinction between it and the digraph $\langlech\rangle$ (pronounced or ). Other diacritics used in Manx included â, ê, ï, etc. to mark the distinction between two similarly spelled words but with slightly differing pronunciation.
 * Irish uses only acute accents to mark long vowels, following the 1948 spelling reform. Lenition is indicated using an overdot in Gaelic type: in Roman type, a suffixed $⟨h⟩$ is used.
 * Breton does not have a single orthography (spelling system), but uses diacritics for a number of purposes. The diaeresis is used to mark that two vowels are pronounced separately and not as a diphthong/digraph. The circumflex is used to mark long vowels, but usually only when the vowel length is not predictable by phonology. Nasalization of vowels may be marked with a tilde, or following the vowel with the letter <ñ>. The plural suffix -où is used as a unified spelling to represent a suffix with a number of pronunciations in different dialects, and to distinguish this suffix from the digraph  which is pronounced as . An apostrophe is used to distinguish c'h, pronounced as the digraph  is used in other Celtic languages, from the French-influenced digraph ch, pronounced.

Finno-Ugric

 * Estonian has a distinct letter õ, which contains a tilde. Estonian "dotted vowels" ä, ö, ü are similar to German, but these are also distinct letters, not like German umlauted letters. All four have their own place in the alphabet, between w and x. Carons in š or ž appear only in foreign proper names and loanwords. Also these are distinct letters, placed in the alphabet between s and t.
 * Finnish uses dotted (umlauted) vowels (ä and ö). As in Swedish and Estonian, these are regarded as individual letters, rather than vowel + umlaut combinations (as happens in German). It also uses the characters å, š and ž in foreign names and loanwords. In the Finnish and Swedish alphabets, å, ä and ö collate as separate letters after z, the others as variants of their base letter.
 * Hungarian uses the umlaut, the acute and double acute accent (unique to Hungarian): (ö, ü), (á, é, í, ó, ú) and (ő, ű). The acute accent indicates the long form of a vowel (in case of i/í, o/ó, u/ú) while the double acute performs the same function for ö and ü. The acute accent can also indicate a different sound (more open, like in case of a/á, e/é). Both long and short forms of the vowels are listed separately in the Hungarian alphabet, but members of the pairs a/á, e/é, i/í, o/ó, ö/ő, u/ú and ü/ű are collated in dictionaries as the same letter.
 * Livonian has the following letters: ā, ä, ǟ, ḑ, ē, ī, ļ, ņ, ō, ȯ, ȱ, õ, ȭ, ŗ, š, ț, ū, ž.

Germanic

 * German uses the umlaut: letters $⟨ä, ö, ü⟩$, used to indicate the fronting of back vowels.
 * Dutch uses acute, circumflex, grave and diaeresis diacritics with most vowels and cedilla with c, as in French. This results in á, à, ä, é, è, ê, ë, í, î, ï, ó, ô, ö, ú, û, ü and ç. This is mostly on words (and names) originating from French (like crème, café, gêne, façade). The acute accent is also used to stress the vowel (like één). The two dots diacritic (¨) is used as a diaeresis (indicating a vowel hiatus that splits the two vowels, e.g., reële, reünie, coördinatie), rather than to indicate an umlaut as used in German.
 * Afrikaans uses 16 additional vowels, both uppercase and lowercase: á,	ä, é, è, ê, ë, í, î, ï, ŉ, ó, ô, ö, ú, û, ü, ý.
 * Faroese uses acutes and other special letters. All are considered separate letters and have their own place in the alphabet: á, í, ó, ú, ý and ø.
 * Icelandic uses acutes and other special letters. All are considered separate letters, and have their own place in the alphabet: á, é, í, ó, ú, ý, and ö.
 * Danish and Norwegian use additional characters like the o-slash ø and the a-overring å. These letters come after z and æ in the order ø, å. Historically, the å has developed from a ligature by writing a small superscript a over a lowercase a; if an å character is unavailable, some Scandinavian languages allow the substitution of a doubled a. The Scandinavian languages collate these letters after z, but have different collation standards.
 * Swedish uses a-diaeresis (ä) and o-diaeresis (ö) in the place of ash (æ) and slashed o (ø) in addition to the a-overring (å). Historically, the diaeresis for the Swedish letters ä and ö, like the German umlaut, developed from a small Gothic e written above the letters. These letters are collated after z, in the order å, ä, ö.

Romance

 * In Asturian, Galician and Spanish, the character ñ is a letter and collated between n and o.
 * Asturian uses Ḷ (lower case ḷ), and Ḥ (lower case ḥ)
 * Catalan uses the acute accent é, í, ó, ú, the grave accent à, è, ò, the diaeresis ï, ü, the cedilla ç, and the interpunct l·l. In Valencian, the circumflex â, ê, î, ô, û may also be used.
 * Corsican uses the following in its alphabet: À/à, È/è, Ì/ì, Ò/ò, Ù/ù.
 * French uses four diacritics appearing on vowels (circumflex, acute, grave, diaeresis) and the cedilla appearing in "ç".
 * Italian uses two diacritics appearing on vowels (acute, grave)
 * Leonese: could use ñ or nn.
 * Portuguese uses a tilde with the vowels $⟨a⟩$ and $⟨o⟩$ and a cedilla with c.
 * Romanian uses a breve on the letter a (ă) to indicate the sound schwa, as well as a circumflex over the letters a (â) and i (î) for the sound . Romanian also writes a comma below the letters s (ș) and t (ț) to represent the sounds and , respectively. These characters are collated after their non-diacritic equivalent.
 * Spanish uses acute accents (á, é, í, ó, ú) to indicate stress falling on a different syllable than the one it would fall on based on default rules, and to distinguish certain one-syllable homonyms (e.g. el (masculine singular definite article) and él "he"). Diaeresis is used on u only, to distinguish the combinations gue, gui from güe, güi, e.g. vergüenza, lingüística. The tilde on $⟨ñ⟩$ is not considered a diacritic as $⟨ñ⟩$ is considered a distinct letter from $⟨n⟩$, not a mutated form of it.

Slavic

 * The Croatian alphabet has the symbols č, ć, đ, š and ž, which are considered separate letters and are listed as such in dictionaries and other contexts in which words are listed according to alphabetical order. It also has one digraph including a diacritic, dž, which is also alphabetized independently, and follows d and precedes đ in the alphabetical order.
 * The Czech alphabet uses the acute (á é í ó ú ý), caron (č ď ě ň ř š ť ž), and for one letter (ů) the ring. (In ď and ť the caron is modified to look rather like an apostrophe.) Letter with caron are considered separate letters, whereas vowels are considered only as longer variants of the unaccented letters. Acute does not affect alphabetical order, letters with caron are ordered after original counterparts.
 * Polish has the following letters: ą ć ę ł ń ó ś ź ż. These are considered to be separate letters: each of them is placed in the alphabet immediately after its Latin counterpart (e.g. ą between a and b), ź and ż are placed after z in that order.
 * The Serbian Cyrillic alphabet has no diacritics, instead it has a grapheme (glyph) for every letter of its Croatian counterpart (including Croatian letters with diacritics and the digraphs dž, lj and nj).
 * The Slovak alphabet uses the acute (á é í ó ú ý ĺ ŕ), caron (č ď ľ ň š ť ž dž), umlaut (ä) and circumflex accent (ô). All of those are considered separate letters and are placed directly after the original counterpart in the alphabet.
 * The basic Slovenian alphabet has the symbols č, š, and ž, which are considered separate letters and are listed as such in dictionaries and other contexts in which words are listed according to alphabetical order. Letters with a caron are placed right after the letters as written without the diacritic. The letter đ may be used in non-transliterated foreign words, particularly names, and is placed after č and before d.

Turkic

 * Azerbaijani includes the distinct Turkish alphabet letters Ç, Ğ, I, İ, Ö, Ş and Ü.
 * Crimean Tatar includes the distinct Turkish alphabet letters Ç, Ğ, I, İ, Ö, Ş and Ü. Unlike Turkish, Crimean Tatar also has the letter Ñ.
 * Gagauz includes the distinct Turkish alphabet letters Ç, Ğ, I, İ, Ö and Ü. Unlike Turkish, Gagauz also has the letters Ä, Ê Ș and Ț. Ș and Ț are derived from the Romanian alphabet for the same sounds. Sometime the Turkish Ş may be used instead of Ș.
 * Turkish uses a G with a breve (Ğ), two letters with an umlaut (Ö and Ü, representing two rounded front vowels), two letters with a cedilla (Ç and Ş, representing the affricate and the fricative ), and also possesses a dotted capital İ (and a dotless lowercase ı representing a high unrounded back vowel). In Turkish each of these are separate letters, rather than versions of other letters, where dotted capital İ and lower case i are the same letter, as are dotless capital I and lowercase ı. Typographically, Ç and Ş are sometimes rendered with a subdot, as in Ṣ; when a hook is used, it tends to have more a comma shape than the usual cedilla. The new Azerbaijani, Crimean Tatar, and Gagauz alphabets are based on the Turkish alphabet and its same diacriticized letters, with some additions.
 * Turkmen includes the distinct Turkish alphabet letters Ç, Ö, Ş and Ü. In addition, Turkmen uses A with diaeresis (Ä) to represent, N with caron (Ň) to represent the velar nasal , Y with acute (Ý) to represent the palatal approximant , and Z with caron (Ž) to represent.

Other

 * Albanian has two special letters Ç and Ë upper and lowercase. They are placed next to the most similar letters in the alphabet, c and e correspondingly.
 * Esperanto has the symbols ŭ, ĉ, ĝ, ĥ, ĵ and ŝ, which are included in the alphabet, and considered separate letters.
 * Filipino also has the character ñ as a letter and is collated between n and o.
 * Modern Greenlandic does not use any diacritics, although ø and å are used to spell loanwords, especially from Danish and English. From 1851 until 1973, Greenlandic was written in an alphabet invented by Samuel Kleinschmidt, where long vowels and geminate consonants were indicated by diacritics on vowels (in the case of consonant gemination, the diacritics were placed on the vowel preceding the affected consonant). For example, the name Kalaallit Nunaat was spelled Kalâdlit Nunât. This scheme uses the circumflex (◌̂) to indicate a long vowel (e.g. ; modern: ), an acute accent (◌́) to indicate gemination of the following consonant: (i.e. ; modern: ) and, finally, a tilde (◌̃) or a grave accent (◌̀), depending on the author, indicates vowel length and gemination of the following consonant (e.g. ; modern: )., used only before , are now written  in Greenlandic.
 * Hawaiian uses the kahakō (macron) over vowels, although there is some disagreement over considering them as individual letters. The kahakō over a vowel can completely change the meaning of a word that is spelled the same but without the kahakō.
 * Kurdish uses the symbols Ç, Ê, Î, Ş and Û with other 26 standard Latin alphabet symbols.
 * Lakota alphabet uses the caron for the letters č, ȟ, ǧ, š, and ž. It also uses the acute accent for stressed vowels á, é, í, ó, ú, áŋ, íŋ, úŋ.
 * Malay uses some diacritics such as á, ā, ç, í, ñ, ó, š, ú. Uses of diacritics was continued until late 19th century except ā and ē.
 * Maltese uses a C, G, and Z with a dot over them (Ċ, Ġ, Ż), and also has an H with an extra horizontal bar. For uppercase H, the extra bar is written slightly above the usual bar. For lowercase H, the extra bar is written crossing the vertical, like a t, and not touching the lower part (Ħ, ħ). The above characters are considered separate letters. The letter 'c' without a dot has fallen out of use due to redundancy. 'Ċ' is pronounced like the English 'ch' and 'k' is used as a hard c as in 'cat'. 'Ż' is pronounced just like the English 'Z' as in 'Zebra', while 'Z' is used to make the sound of 'ts' in English (like 'tsunami' or 'maths'). 'Ġ' is used as a soft 'G' like in 'geometry', while the 'G' sounds like a hard 'G' like in 'log'. The digraph 'għ' (called għajn after the Arabic letter name ʻayn for غ) is considered separate, and sometimes ordered after 'g', whilst in other volumes it is placed between 'n' and 'o' (the Latin letter 'o' originally evolved from the shape of Phoenician ʻayin, which was traditionally collated after Phoenician nūn).
 * The romanization of Syriac uses the altered letters of. Ā, Č, Ḏ, Ē, Ë, Ġ, Ḥ, Ō, Š, Ṣ, Ṭ, Ū, Ž alongside the 26 standard Latin alphabet symbols.
 * Vietnamese uses the horn diacritic for the letters ơ and ư; the circumflex for the letters â, ê, and ô; the breve for the letter ă; and a bar through the letter đ. Separately, it also has á, à, ả, ã and ạ, the five tones used for vowels besides the flat tone 'a'.

Cyrillic letters

 * Belarusian and Uzbek Cyrillic have a letter ў.
 * Belarusian, Bulgarian, Russian and Ukrainian have the letter й.
 * Belarusian and Russian have the letter ё. In Russian, this letter is usually replaced by е, although it has a different pronunciation. The use of е instead of ё does not affect the pronunciation. Ё is always used in children's books and in dictionaries. A minimal pair is все (vs'e, "everybody" pl.) and всё (vs'o, "everything" n. sg.). In Belarusian the replacement by е is a mistake; in Russian, it is permissible to use either е or ё for ё but the former is more common in everyday writing (as opposed to instructional or juvenile writing).
 * The Cyrillic Ukrainian alphabet has the letters ґ, й and ї. Ukrainian Latynka has many more.
 * Macedonian has the letters ќ and ѓ.
 * In Bulgarian and Macedonian the possessive pronoun ѝ (ì, "her") is spelled with a grave accent in order to distinguish it from the conjunction и (i, "and").
 * The acute accent ́ above any vowel in Cyrillic alphabets is used in dictionaries, books for children and foreign learners to indicate the word stress, it also can be used for disambiguation of similarly spelled words with different lexical stresses.

English
English is one of the few European languages that does not have many words that contain diacritical marks. Instead, digraphs are the main way the Modern English alphabet adapts the Latin to its phonemes. Exceptions are unassimilated foreign loanwords, including borrowings from French (and, increasingly, Spanish, like jalapeño and piñata); however, the diacritic is also sometimes omitted from such words. Loanwords that frequently appear with the diacritic in English include café, résumé or resumé (a usage that helps distinguish it from the verb resume), soufflé, and naïveté (see English terms with diacritical marks). In older practice (and even among some orthographically-conservative modern writers), one may see examples such as élite, mêlée and rôle.

English speakers and writers once used the diaeresis more often than now in words such as coöperation (from Fr. coopération), zoölogy (from Grk. zoologia), and seeër (now more commonly see-er or simply seer) as a way of indicating that adjacent vowels belonged to separate syllables, but this practice has become far less common. The New Yorker magazine is a major publication that continues to use the diaeresis in place of a hyphen for clarity and economy of space.

A few English words, often when used out of context, especially in isolation, can only be distinguished from other words of the same spelling by using a diacritic or modified letter. These include exposé, lamé, maté, öre, øre, résumé and rosé. In a few words, diacritics that did not exist in the original have been added for disambiguation, as in maté (from Sp. and Port. mate), saké (the standard Romanization of the Japanese has no accent mark), and Malé (from Dhivehi މާލެ), to clearly distinguish them from the English words mate, sake, and male.

The acute and grave accents are occasionally used in poetry and lyrics: the acute to indicate stress overtly where it might be ambiguous (rébel vs. rebél) or nonstandard for metrical reasons (caléndar), the grave to indicate that an ordinarily silent or elided syllable is pronounced (warnèd, parlìament).

In certain personal names such as Renée and Zoë, often two spellings exist, and the person's own preference will be known only to those close to them. Even when the name of a person is spelled with a diacritic, like Charlotte Brontë, this may be dropped in English-language articles, and even in official documents such as passports, due either to carelessness, the typist not knowing how to enter letters with diacritical marks, or technical reasons (California, for example, does not allow names with diacritics, as the computer system cannot process such characters). They also appear in some worldwide company names and/or trademarks, such as Nestlé and Citroën.

Other languages
The following languages have letter-diacritic combinations that are not considered independent letters.
 * Afrikaans uses a diaeresis to mark vowels that are pronounced separately and not as one would expect where they occur together, for example voel (to feel) as opposed to voël (bird). The circumflex is used in ê, î, ô and û generally to indicate long close-mid, as opposed to open-mid vowels, for example in the words wêreld (world) and môre (morning, tomorrow). The acute accent is used to add emphasis in the same way as underlining or writing in bold or italics in English, for example Dit is jóú boek (It is your book). The grave accent is used to distinguish between words that are different only in placement of the stress, for example appel (apple) and appèl (appeal) and in a few cases where it makes no difference to the pronunciation but distinguishes between homophones. The two most usual cases of the latter are in the sayings òf... òf (either... or) and nòg... nòg (neither... nor) to distinguish them from of (or) and nog (again, still).
 * Aymara uses a diacritical horn over p, q, t, k, ch.
 * Catalan has the following composite characters: à, ç, é, è, í, ï, ó, ò, ú, ü, l·l. The acute and the grave indicate stress and vowel height, the cedilla marks the result of a historical palatalization, the diaeresis indicates either a hiatus, or that the letter u is pronounced when the graphemes gü, qü are followed by e or i, the interpunct (·) distinguishes the different values of ll/l·l.
 * Some orthographies of Cornish such as Kernowek Standard and Unified Cornish use diacritics, while others such as Kernewek Kemmyn and the Standard Written Form do not (or only use them optionally in teaching materials).
 * Dutch uses the diaeresis. For example, in ruïne it means that the u and the i are separately pronounced in their usual way, and not in the way that the combination ui is normally pronounced. Thus it works as a separation sign and not as an indication for an alternative version of the i. Diacritics can be used for emphasis (érg koud for very cold) or for disambiguation between a number of words that are spelled the same when context does not indicate the correct meaning (één appel = one apple, een appel = an apple; vóórkomen = to occur, voorkómen = to prevent). Grave and acute accents are used on a very small number of words, mostly loanwords. The ç also appears in some loanwords.
 * Faroese. Non-Faroese accented letters are not added to the Faroese alphabet. These include é, ö, ü, å and recently also letters like š, ł, and ć.
 * Filipino has the following composite characters: á, à, â, é, è, ê, í, ì, î, ó, ò, ô, ú, ù, û. Everyday use of diacritics for Filipino is, however, uncommon, and meant only to distinguish between homonyms between a word with the usual penultimate stress and one with a different stress placement. This aids both comprehension and pronunciation if both are relatively adjacent in a text, or if a word is itself ambiguous in meaning. The letter ñ ("eñe") is not a n with a diacritic, but rather collated as a separate letter, one of eight borrowed from Spanish. Diacritics appear in Spanish loanwords and names observing Spanish orthography rules.
 * Finnish. Carons in š and ž appear only in foreign proper names and loanwords, but may be substituted with sh or zh if and only if it is technically impossible to produce accented letters in the medium. Contrary to Estonian, š and ž are not considered distinct letters in Finnish.
 * French uses five diacritics. The grave (accent grave) marks the sound when over an e, as in père ("father") or is used to distinguish words that are otherwise homographs such as a/à ("has"/"to") or ou/où ("or"/"where"). The acute (accent aigu) is only used in "é", modifying the "e" to make the sound, as in étoile ("star"). The circumflex (accent circonflexe) generally denotes that an S once followed the vowel in Old French or Latin, as in fête ("party"), the Old French being feste and the Latin being festum. Whether the circumflex modifies the vowel's pronunciation depends on the dialect and the vowel. The cedilla (cédille) indicates that a normally hard "c" (before the vowels "a", "o", and "u") is to be pronounced , as in ça ("that"). The diaeresis diacritic (tréma) indicates that two adjacent vowels that would normally be pronounced as one are to be pronounced separately, as in Noël ("Christmas").
 * Galician vowels can bear an acute (á, é, í, ó, ú) to indicate stress or difference between two otherwise same written words (é, 'is' vs. e, 'and'), but the diaeresis is only used with ï and ü to show two separate vowel sounds in pronunciation. Only in foreign words may Galician use other diacritics such as ç (common during the Middle Ages), ê, or à.
 * German uses the three umlauted characters ä, ö and ü. These diacritics indicate vowel changes. For instance, the word Ofen "oven" has the plural Öfen . The mark originated as a superscript e; a handwritten blackletter e resembles two parallel vertical lines, like a diaeresis. Due to this history, "ä", "ö" and "ü" can be written as "ae", "oe" and "ue" respectively, if the umlaut letters are not available.
 * Hebrew has many various diacritic marks known as niqqud that are used above and below script to represent vowels. These must be distinguished from cantillation, which are keys to pronunciation and syntax.
 * The International Phonetic Alphabet uses diacritic symbols and characters to indicate phonetic features or secondary articulations.
 * Irish uses the acute to indicate that a vowel is long: á, é, í, ó, ú. It is known as síneadh fada "long sign" or simply fada "long" in Irish. In the older Gaelic type, overdots are used to indicate lenition of a consonant: ḃ, ċ, ḋ, ḟ, ġ, ṁ, ṗ, ṡ, ṫ.
 * Italian mainly has the acute and the grave (à, è/é, ì, ò/ó, ù), typically to indicate a stressed syllable that would not be stressed under the normal rules of pronunciation but sometimes also to distinguish between words that are otherwise spelled the same way (e.g. "e", and; "è", is). Despite its rare use, Italian orthography allows the circumflex (î) too, in two cases: it can be found in old literary context (roughly up to 19th century) to signal a syncope (fêro→fecero, they did), or in modern Italian to signal the contraction of ″-ii″ due to the plural ending -i whereas the root ends with another -i; e.g., s. demonio, p. demonii→demonî; in this case the circumflex also signals that the word intended is not demoni, plural of "demone" by shifting the accent (demònî, "devils"; dèmoni, "demons").
 * Lithuanian uses the acute, grave and tilde in dictionaries to indicate stress types in the language's pitch accent system.
 * Maltese also uses the grave on its vowels to indicate stress at the end of a word with two syllables or more:– lowercase letters: à, è, ì, ò, ù; capital letters: À, È, Ì, Ò, Ù
 * Māori makes use of macrons to mark long vowels.
 * Occitan has the following composite characters: á, à, ç, é, è, í, ï, ó, ò, ú, ü, n·h, s·h. The acute and the grave indicate stress and vowel height, the cedilla marks the result of a historical palatalization, the diaeresis indicates either a hiatus, or that the letter u is pronounced when the graphemes gü, qü are followed by e or i, and the interpunct (·) distinguishes the different values of nh/n·h and sh/s·h (i.e., that the letters are supposed to be pronounced separately, not combined into "ny" and "sh").
 * Portuguese has the following composite characters: à, á, â, ã, ç, é, ê, í, ó, ô, õ, ú. The acute and the circumflex indicate stress and vowel height, the grave indicates crasis, the tilde represents nasalization, and the cedilla marks the result of a historical lenition.
 * Acutes are also used in Slavic language dictionaries and textbooks to indicate lexical stress, placed over the vowel of the stressed syllable. This can also serve to disambiguate meaning (e.g., in Russian писа́ть (pisáť) means "to write", but пи́сать (písať) means "to piss"), or "бо́льшая часть" (the biggest part) vs "больша́я часть" (the big part).
 * Spanish uses the acute and the diaeresis. The acute is used on a vowel in a stressed syllable in words with irregular stress patterns. It can also be used to "break up" a diphthong as in tío (pronounced, rather than as it would be without the accent). Moreover, the acute can be used to distinguish words that otherwise are spelled alike, such as si ("if") and sí ("yes"), and also to distinguish interrogative and exclamatory pronouns from homophones with a different grammatical function, such as donde/¿dónde? ("where"/"where?") or como/¿cómo? ("as"/"how?"). The acute may also be used to avoid typographical ambiguity, as in 1 ó 2 ("1 or 2"; without the acute this might be interpreted as "1 0 2". The diaeresis is used only over u (ü) for it to be pronounced  in the combinations gue and gui, where u is normally silent, for example ambigüedad. In poetry, the diaeresis may be used on i and u as a way to force a hiatus. As foreshadowed above, in nasal ñ the tilde (squiggle) is not considered a diacritic sign at all, but a composite part of a distinct glyph, with its own chapter in the dictionary: a glyph that denotes the 15th letter of the Spanish alphabet.
 * Swedish uses the acute to show non-standard stress, for example in kafé (café) and resumé (résumé). This occasionally helps resolve ambiguities, such as ide (hibernation) versus idé (idea). In these words, the acute is not optional. Some proper names use non-standard diacritics, such as Carolina Klüft and Staël von Holstein. For foreign loanwords the original accents are strongly recommended, unless the word has been infused into the language, in which case they are optional. Hence crème fraîche but ampere. Swedish also has the letters å, ä, and ö, but these are considered distinct letters, not a and o with diacritics.
 * Tamil does not have any diacritics in itself, but uses the Arabic numerals 2, 3 and 4 as diacritics to represent aspirated, voiced, and voiced-aspirated consonants when Tamil script is used to write long passages in Sanskrit.
 * Thai has its own system of diacritics derived from Indian numerals, which denote different tones.
 * Vietnamese uses the acute (dấu sắc), the grave (dấu huyền), the tilde (dấu ngã), the underdot (dấu nặng) and the hook above (dấu hỏi) on vowels as tone indicators.
 * Welsh uses the circumflex, diaeresis, acute, and grave on its seven vowels a, e, i, o, u, w, y. The most common is the circumflex (which it calls to bach, meaning "little roof", or acen grom "crooked accent", or hirnod "long sign") to denote a long vowel, usually to disambiguate it from a similar word with a short vowel or a semivowel. The rarer grave accent has the opposite effect, shortening vowel sounds that would usually be pronounced long. The acute accent and diaeresis are also occasionally used, to denote stress and vowel separation respectively. The w-circumflex ŵ and the y-circumflex ŷ are among the most commonly accented characters in Welsh, but unusual in languages generally, and were until recently very hard to obtain in word-processed and HTML documents.

Transliteration
Several languages that are not written with the Roman alphabet are transliterated, or romanized, using diacritics. Examples:
 * Arabic has several romanisations, depending on the type of the application, region, intended audience, country, etc. many of them extensively use diacritics, e.g., some methods use an underdot for rendering emphatic consonants (ṣ, ṭ, ḍ, ẓ, ḥ). The macron is often used to render long vowels. š is often used for, ġ for.
 * Chinese has several romanizations that use the umlaut, but only on u (ü). In Hanyu Pinyin, the four tones of Mandarin Chinese are denoted by the macron (first tone), acute (second tone), caron (third tone) and grave (fourth tone) diacritics. Example: ā, á, ǎ, à.
 * Romanized Japanese (Rōmaji) occasionally uses macrons to mark long vowels. The Hepburn romanization system uses macrons to mark long vowels, and the Kunrei-shiki and Nihon-shiki systems use a circumflex.
 * Sanskrit, as well as many of its descendants, like Hindi and Bengali, uses a lossless romanization system, IAST. This includes several letters with diacritical markings, such as the macron (ā, ī, ū), over- and underdots (ṛ, ḥ, ṃ, ṇ, ṣ, ṭ, ḍ) as well as a few others (ś, ñ).

Orthographic
Possibly the greatest number of combining diacritics required to compose a valid character in any Unicode language is 8, for the "well-known grapheme cluster in Tibetan and Ranjana scripts" or HAKṢHMALAWARAYAṀ.

It consists of

An example of rendering, may be broken depending on browser:

"ཧྐྵྨླྺྼྻྂ"

Unorthographic/ornamental
Some users have explored the limits of rendering in web browsers and other software by "decorating" words with excessive nonsensical diacritics per character to produce so-called Zalgo text.

List of diacritics in Unicode
Diacritics for Latin script in Unicode:

title: Diacritic


text:
Digraph

Digraph, often misspelled as diagraph, may refer to:

 * Digraph (orthography), a pair of characters used together to represent a single sound, such as "sh" in English
 * Ligature (writing), the joining of two letters as a single glyph, such as "æ"
 * Digraph (computing), a group of two characters in computer source code to be treated as a single character
 * A directed graph, in graph theory
 * Digraph, a component of a CIA cryptonym, a covert code name
 * Digraph, a two-letter ISO 639-1 language code

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

title: Digraph


text:
Didgeridoo

The didgeridoo (also spelt didjeridu, among other variants) is a wind instrument, played with vibrating lips to produce a continuous drone while using a special breathing technique called circular breathing. The didgeridoo was developed by Aboriginal peoples of northern Australia at least 1,000 years ago, and is now in use around the world, though still most strongly associated with Indigenous Australian music. In the Yolŋu languages of the indigenous people of northeast Arnhem Land the name for the instrument is the yiḏaki, or more recently by some, mandapul. In the Bininj Kunwok language of West Arnhem Land it is known as mako.

A didgeridoo is usually cylindrical or conical, and can measure anywhere from 1 to 3 m long. Most are around 1.2 m long. Generally, the longer the instrument, the lower its pitch or key. Flared instruments play a higher pitch than unflared instruments of the same length.

History
There are no reliable sources of the exact age of the didgeridoo. Archaeological studies suggest that people of the Kakadu region in Northern Australia have been using the didgeridoo for less than 1,000 years, based on the dating of rock art paintings. A clear rock painting in Ginga Wardelirrhmeng, on the northern edge of the Arnhem Land plateau, from the freshwater period (that had begun 1500 years ago) shows a didgeridoo player and two song-men participating in an Ubarr ceremony. It is thus thought that it was developed by Aboriginal peoples of northern Australia, possibly in Arnhem Land.

T. B. Wilson's Narrative of a Voyage Round the World (1835) includes a drawing of an Aboriginal man from Raffles Bay on the Cobourg Peninsula (about 350 km east of Darwin) playing the instrument. Others observed such an instrument in the same area, made of bamboo and about 3 ft long. In 1893, English palaeontologist Robert Etheridge, Junior observed the use of "three very curious trumpets" made of bamboo in northern Australia. There were then two native species of bamboo growing along the Adelaide River, Northern Territory".

According to A. P. Elkin, in 1938, the instrument was "only known in the eastern Kimberley [region in Western Australia] and the northern third of the Northern Territory".

Etymology
The name didgeridoo is not of Aboriginal Australian linguistic origin and is considered to be an onomatopoetic word. The earliest occurrences of the word in print include a 1908 edition of the Hamilton Spectator referring to a did-gery-do' (hollow bamboo)", a 1914 edition of The Northern Territory Times and Gazette, and a 1919 issue of Smith's Weekly, in which it was referred to as a "didjerry" and was said to produce the sound "didjerry, didjerry, didjerry and so on ad infinitum".

A rival explanation, that didgeridoo is a corruption of the Irish phrase dúdaire dubh or Scottish Gaelic dùdaire dúth, is controversial. Irish dúdaire or dúidire, and Scottish Gaelic dùdaire, are nouns that, depending on the context, may mean "trumpeter", "hummer", "crooner" or "puffer", while Irish dubh means "black", and Scottish Gaelic dúth means "native".

Other names
There are numerous names for the instrument among the Aboriginal peoples of northern Australia, none of which closely resemble the word "didgeridoo" (see below). Some didgeridoo enthusiasts, scholars and Aboriginal people advocate using local language names for the instrument.

Yiḏaki (transcribed yidaki in English, sometimes spelt yirdaki) is one of the most commonly used names although, strictly speaking, it refers to a specific type of the instrument made and used by the Yolngu peoples of north-east Arnhem Land. Some Yolngu people began using the word mandapul after 2011, out of respect for the passing of a Manggalili man who had a name sounding similar to yidaki.

In west Arnhem Land, it is known as a mako, a name popularised by virtuoso player David Blanasi, a Bininj man, whose language was Kunwinjku, and who brought the didgeridoo to world prominence. However the mako is slightly different from the Yiḏaki: usually shorter, and sounding somewhat different – a slightly fuller and richer sound, but without the "overtone" note.

There are at least 45 names for the didgeridoo, several of which suggest its original construction of bamboo, such as bambu, bombo, kambu, and pampu, which are still used in the lingua franca by some Aboriginal people. The following are some of the more common regional names.

Description and construction
A didgeridoo is usually cylindrical or conical, and can measure anywhere from 1 to 3 m long. Most are around 1.2 m long. Generally, the longer the instrument, the lower its pitch or key. However, flared instruments play a higher pitch than unflared instruments of the same length.

The didgeridoo is classified as a wind instrument and is similar in form to a straight trumpet, but made of wood. It has also been called a dronepipe.

Traditional
Traditional didgeridoos are usually made from hardwoods, especially the various eucalyptus species that are endemic to northern and central Australia. Generally the main trunk of the tree is harvested, though a substantial branch may be used instead. Traditional didgeridoo makers seek suitably hollow live trees in areas with obvious termite activity. Termites attack these living eucalyptus trees, removing only the dead heartwood of the tree, as the living sapwood contains a chemical that repels the insects. Various techniques are employed to find trees with a suitable hollow, including knowledge of landscape and termite activity patterns, and a kind of tap or knock test, in which the bark of the tree is peeled back, and a fingernail or the blunt end of a tool, such as an axe, is knocked against the wood to determine if the hollow produces the right resonance. Once a suitably hollow tree is found, it is cut down and cleaned out, the bark is taken off, the ends trimmed, and the exterior is shaped; this results in a finished instrument. A rim of beeswax may be applied to the mouthpiece end.

Modern
Non-traditional didgeridoos can be made from native or non-native hard woods (typically split, hollowed and rejoined), glass, fibreglass, metal, agave, clay, resin, PVC piping and carbon fibre. These typically have an upper inside diameter of around 3 cm down to a bell end of anywhere between 5 and 20 cm and have a length corresponding to the desired key. The end of the pipe can be shaped and smoothed to create a comfortable mouthpiece or an added mouthpiece can be made of any shaped and smoothed material such as rubber, a rubber stopper with a hole or beeswax.

Modern didgeridoo designs are distinct from the traditional Australian Aboriginal didgeridoo, and are innovations recognised by musicologists. Didgeridoo design innovation started in the late 20th century, using non-traditional materials and non-traditional shapes. The practice has sparked, however, a good deal of debate among indigenous practitioners and non-indigenous people about its aesthetic, ethical, and legal issues.

Decoration
Didgeridoos can be painted by their maker or a dedicated artist using traditional or modern paints while others retain the natural wood grain design with minimal or no decoration.

Playing
A didgeridoo can be played simply by producing a vibrating sound of the lips to produce the basic drone. More advanced playing involves the technique known as circular breathing. The circular breathing technique requires breathing in through the nose whilst simultaneously using the muscles of the cheeks to compress the cheeks and release the stored air out of the mouth. By using this technique, a skilled player can replenish the air in their lungs, and with practice they can sustain a note for as long as desired. Recordings exist of modern didgeridoo players playing continuously for more than 40 minutes; Mark Atkins on Didgeridoo Concerto (1994) plays for over 50 minutes continuously. Although circular breathing does eliminate the need to stop playing to take a breath, discomfort might still develop during a period of extended play due to chapped lips or other oral discomfort.

The didgeridoo functions "...as an aural kaleidoscope of timbres" and "the extremely difficult virtuoso techniques developed by expert performers find no parallel elsewhere."

The didgeridoo virtuoso and composer William Barton has expanded the role of the instrument in the concert hall both with his own orchestral and chamber music works and with those written or arranged for him by prominent Australian composer Peter Sculthorpe.

Physics and operation

A termite-bored didgeridoo has an irregular shape that, overall, usually increases in diameter towards the lower end. This shape means that its resonances occur at frequencies that are not harmonically spaced in frequency. This contrasts with the harmonic spacing of the resonances in a cylindrical plastic pipe, whose resonant frequencies fall in the ratio 1:3:5 etc. The second resonance of a didgeridoo (the note sounded by overblowing) is usually around an 11th higher than the fundamental frequency (a frequency ratio of 8:3).

The vibration produced by the player's lips has harmonics in the ratio 1:2:3 etc. However, the non-harmonic spacing of the instrument's resonances means that the harmonics of the fundamental note are not systematically assisted by instrument's resonances, as is usually the case for Western wind instruments (e.g., in the low range of the clarinet, the 1st, 3rd, and 5th harmonics of the reed are assisted by resonances of the bore).

Sufficiently strong resonances of the vocal tract can strongly influence the timbre of the instrument. At some frequencies, whose values depend on the position of the player's tongue, resonances of the vocal tract inhibit the oscillatory flow of air into the instrument. Bands of frequencies that are not thus inhibited produce formants in the output sound. These formants, and especially their variation during the inhalation and exhalation phases of circular breathing, give the instrument its readily recognisable sound.

Other variations in the didgeridoo's sound can be made by adding vocalisations to the drone. Most of the vocalisations are related to sounds emitted by Australian animals, such as the dingo or the kookaburra. To produce these sounds, the players use their vocal folds to produce the sounds of the animals whilst continuing to blow air through the instrument. The results range from very high-pitched sounds to much lower sounds involving interference between the lip and vocal fold vibrations. Adding vocalisations increases the complexity of the playing.

In popular culture
Charlie McMahon, who formed the group Gondwanaland, was one of the first non-Aboriginal players to gain fame as a professional didgeridoo player. He has toured internationally with Midnight Oil. He invented the didjeribone, a sliding didgeridoo made from two lengths of plastic tubing; its playing style is somewhat in the manner of a trombone.

The didgeridoo has been used by a number of modern bands in various types of music.

It was featured on the British children's TV series Blue Peter.

Industrial music bands like Test Dept use the didgeridoo.

Early songs by the acid jazz band Jamiroquai featured didgeridoo player Wallis Buchanan, including the band's first single "When You Gonna Learn", which features prominent didgeridoo in the introduction and solo sections.

Ambient artist Steve Roach uses it in his collaborative work Australia: Sound of the Earth with Australian Aboriginal artist David Hudson and cellist Sarah Hopkins, as well as Dreamtime Return.

It is used in the Indian song "Jaane Kyon" from the film Dil Chahta Hai.

Chris Brooks, lead singer of the New Zealand hard rock band Like a Storm, uses the didgeridoo in some songs, including "Love the Way You Hate Me" from their album Chaos Theory: Part 1 (2012).

Kate Bush made extensive use of the didgeridoo, played by Australian musician Rolf Harris, on her album The Dreaming (1982), which was written and recorded after a holiday in Australia.

Cultural significance
Traditionally, the didgeridoo was played as an accompaniment to ceremonial dancing and singing and for solo or recreational purposes. For Aboriginal peoples of northern Australia, the yidaki is still used to accompany singers and dancers in cultural ceremonies. For the Yolngu people, the yidaki is part of their whole physical and cultural landscape and environment, comprising the people and spirit beings which belong to their country, kinship system and the Yolngu Matha language. It is connected to Yolngu Law and underpinned by ceremony, in song, dance, visual art and stories.

Pair sticks, sometimes called clapsticks (bilma or bimla by some traditional groups), establish the beat for the songs during ceremonies. The rhythm of the didgeridoo and the beat of the clapsticks are precise, and these patterns have been handed down for many generations. In the Wangga genre, the song-man starts with vocals and then introduces bilma to the accompaniment of didgeridoo.

Gender-based traditional prohibition debate
Traditionally, only men play the didgeridoo and sing during ceremonial occasions; playing by women is sometimes discouraged by Aboriginal communities and elders. In 2008, publisher HarperCollins apologised for its book The Daring Book for Girls, which openly encouraged girls to play the instrument after Aboriginal academic Mark Rose described such encouragement as "extreme cultural insensitivity" and "an extreme faux pas... part of a general ignorance that mainstream Australia has about Aboriginal culture." However, Linda Barwick, an ethnomusicologist, said that though traditionally women have not played the didgeridoo in ceremony, in informal situations there is no prohibition in the Dreaming Law. For example, in 1966, ethnomusicologist Alice Marshall Moyle made a recording in Borroloola of Jemima Wimalu, a Mara woman from the Roper River, proficiently playing the didgeridoo. In 1995, musicologist Steve Knopoff observed Yirrkala women performing djatpangarri songs that are traditionally performed by men and in 1996, ethnomusicologist Elizabeth MacKinley reported women of the Yanyuwa group giving public performances.

Although there is no prohibition in the area of the didgeridoo's origin, such restrictions have been applied by other Indigenous communities. The didgeridoo was introduced to the Kimberleys in the early 20th century but it was only much later, such as in Rose's 2008 criticism of The Daring Book for Girls, that Aboriginal men showed adverse reactions to women playing the instrument and prohibitions are especially evident in the South East of Australia. The belief that women are prohibited from playing is widespread among non-Aboriginal people and is also common among Aboriginal communities in Southern Australia; some ethnomusicologists believe that the dissemination of the taboo belief and other misconceptions is a result of commercial agendas and marketing. The majority of commercial didgeridoo recordings available are distributed by multinational recording companies and feature non-Aboriginal people playing a New Age style of music with liner notes promoting the instrument's spirituality which misleads consumers about the didgeridoo's secular role in traditional Aboriginal culture.

The taboo is particularly strong among many Aboriginal groups in the South East of Australia, where it is forbidden and considered "cultural theft" for non-Aboriginal women, and especially performers of New Age music regardless of gender, to play or even touch a didgeridoo.

Health benefits
A 2006 study reported in the British Medical Journal found that learning and practising the didgeridoo helped reduce snoring and obstructive sleep apnea by strengthening muscles in the upper airway, thus reducing their tendency to collapse during sleep. In the study, intervention subjects were trained in and practised didgeridoo playing, including circular breathing and other techniques. Control subjects were asked not to play the instrument. Subjects were surveyed before and after the study period to assess the effects of intervention. A small 2010 study noted marked improvements in the asthma management of 10 Aboriginal adults and children following a six-month programme of once-weekly didgeridoo lessons.

title: Didgeridoo


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Developmental biology

Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism.

Perspectives
The main processes involved in the embryonic development of animals are: tissue patterning (via regional specification and patterned cell differentiation); tissue growth; and tissue morphogenesis.

 * Regional specification refers to the processes that create the spatial patterns in a ball or sheet of initially similar cells. This generally involves the action of cytoplasmic determinants, located within parts of the fertilized egg, and of inductive signals emitted from signaling centers in the embryo. The early stages of regional specification do not generate functional differentiated cells, but cell populations committed to developing to a specific region or part of the organism. These are defined by the expression of specific combinations of transcription factors.
 * Cell differentiation relates specifically to the formation of functional cell types such as nerve, muscle, secretory epithelia, etc. Differentiated cells contain large amounts of specific proteins associated with cell function.
 * Morphogenesis relates to the formation of a three-dimensional shape. It mainly involves the orchestrated movements of cell sheets and of individual cells. Morphogenesis is important for creating the three germ layers of the early embryo (ectoderm, mesoderm, and endoderm) and for building up complex structures during organ development.
 * Tissue growth involves both an overall increase in tissue size, and also the differential growth of parts (allometry) which contributes to morphogenesis. Growth mostly occurs through cell proliferation but also through changes in cell size or the deposition of extracellular materials.

The development of plants involves similar processes to that of animals. However, plant cells are mostly immotile so morphogenesis is achieved by differential growth, without cell movements. Also, the inductive signals and the genes involved are different from those that control animal development.

Generative biology
Generative biology is the generative science that explores the dynamics guiding the development and evolution of a biological morphological form.

Cell differentiation

Cell differentiation is the process whereby different functional cell types arise in development. For example, neurons, muscle fibers and hepatocytes (liver cells) are well known types of differentiated cells. Differentiated cells usually produce large amounts of a few proteins that are required for their specific function and this gives them the characteristic appearance that enables them to be recognized under the light microscope. The genes encoding these proteins are highly active. Typically their chromatin structure is very open, allowing access for the transcription enzymes, and specific transcription factors bind to regulatory sequences in the DNA in order to activate gene expression. For example, NeuroD is a key transcription factor for neuronal differentiation, myogenin for muscle differentiation, and HNF4 for hepatocyte differentiation. Cell differentiation is usually the final stage of development, preceded by several states of commitment which are not visibly differentiated. A single tissue, formed from a single type of progenitor cell or stem cell, often consists of several differentiated cell types. Control of their formation involves a process of lateral inhibition, based on the properties of the Notch signaling pathway. For example, in the neural plate of the embryo this system operates to generate a population of neuronal precursor cells in which NeuroD is highly expressed.

Regeneration
Regeneration indicates the ability to regrow a missing part. This is very prevalent amongst plants, which show continuous growth, and also among colonial animals such as hydroids and ascidians. But most interest by developmental biologists has been shown in the regeneration of parts in free living animals. In particular four models have been the subject of much investigation. Two of these have the ability to regenerate whole bodies: Hydra, which can regenerate any part of the polyp from a small fragment, and planarian worms, which can usually regenerate both heads and tails. Both of these examples have continuous cell turnover fed by stem cells and, at least in planaria, at least some of the stem cells have been shown to be pluripotent. The other two models show only distal regeneration of appendages. These are the insect appendages, usually the legs of hemimetabolous insects such as the cricket, and the limbs of urodele amphibians. Considerable information is now available about amphibian limb regeneration and it is known that each cell type regenerates itself, except for connective tissues where there is considerable interconversion between cartilage, dermis and tendons. In terms of the pattern of structures, this is controlled by a re-activation of signals active in the embryo. There is still debate about the old question of whether regeneration is a "pristine" or an "adaptive" property. If the former is the case, with improved knowledge, we might expect to be able to improve regenerative ability in humans. If the latter, then each instance of regeneration is presumed to have arisen by natural selection in circumstances particular to the species, so no general rules would be expected.

Embryonic development of animals
The sperm and egg fuse in the process of fertilization to form a fertilized egg, or zygote. This undergoes a period of divisions to form a ball or sheet of similar cells called a blastula or blastoderm. These cell divisions are usually rapid with no growth so the daughter cells are half the size of the mother cell and the whole embryo stays about the same size. They are called cleavage divisions.

Mouse epiblast primordial germ cells (see Figure: “The initial stages of human embryogenesis”) undergo extensive epigenetic reprogramming. This process involves genome-wide DNA demethylation, chromatin reorganization and epigenetic imprint erasure leading to totipotency. DNA demethylation is carried out by a process that utilizes the DNA base excision repair pathway.

Morphogenetic movements convert the cell mass into a three layered structure consisting of multicellular sheets called ectoderm, mesoderm and endoderm. These sheets are known as germ layers. This is the process of gastrulation. During cleavage and gastrulation the first regional specification events occur. In addition to the formation of the three germ layers themselves, these often generate extraembryonic structures, such as the mammalian placenta, needed for support and nutrition of the embryo, and also establish differences of commitment along the anteroposterior axis (head, trunk and tail).

Regional specification is initiated by the presence of cytoplasmic determinants in one part of the zygote. The cells that contain the determinant become a signaling center and emit an inducing factor. Because the inducing factor is produced in one place, diffuses away, and decays, it forms a concentration gradient, high near the source cells and low further away. The remaining cells of the embryo, which do not contain the determinant, are competent to respond to different concentrations by upregulating specific developmental control genes. This results in a series of zones becoming set up, arranged at progressively greater distance from the signaling center. In each zone a different combination of developmental control genes is upregulated. These genes encode transcription factors which upregulate new combinations of gene activity in each region. Among other functions, these transcription factors control expression of genes conferring specific adhesive and motility properties on the cells in which they are active. Because of these different morphogenetic properties, the cells of each germ layer move to form sheets such that the ectoderm ends up on the outside, mesoderm in the middle, and endoderm on the inside.

Morphogenetic movements not only change the shape and structure of the embryo, but by bringing cell sheets into new spatial relationships they also make possible new phases of signaling and response between them. In addition, first morphogenetic movements of embryogenesis, such as gastrulation, epiboly and twisting, directly activate pathways involved in endomesoderm specification through mechanotransduction processes. This property was suggested to be evolutionary inherited from endomesoderm specification as mechanically stimulated by marine environmental hydrodynamic flow in first animal organisms (first metazoa). Twisting along the body axis by a left-handed chirality is found in all chordates (including vertebrates) and is addressed by the axial twist theory.

Growth in embryos is mostly autonomous. For each territory of cells the growth rate is controlled by the combination of genes that are active. Free-living embryos do not grow in mass as they have no external food supply. But embryos fed by a placenta or extraembryonic yolk supply can grow very fast, and changes to relative growth rate between parts in these organisms help to produce the final overall anatomy.

The whole process needs to be coordinated in time and how this is controlled is not understood. There may be a master clock able to communicate with all parts of the embryo that controls the course of events, or timing may depend simply on local causal sequences of events.

Metamorphosis
Developmental processes are very evident during the process of metamorphosis. This occurs in various types of animal. Well-known examples are seen in frogs, which usually hatch as a tadpole and metamorphoses to an adult frog, and certain insects which hatch as a larva and then become remodeled to the adult form during a pupal stage.

All the developmental processes listed above occur during metamorphosis. Examples that have been especially well studied include tail loss and other changes in the tadpole of the frog Xenopus, and the biology of the imaginal discs, which generate the adult body parts of the fly Drosophila melanogaster.

Plant development
Plant development is the process by which structures originate and mature as a plant grows. It is studied in plant anatomy and plant physiology as well as plant morphology.

Plants constantly produce new tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant always has embryonic tissues. By contrast, an animal embryo will very early produce all of the body parts that it will ever have in its life. When the animal is born (or hatches from its egg), it has all its body parts and from that point will only grow larger and more mature.

The properties of organization seen in a plant are emergent properties which are more than the sum of the individual parts. "The assembly of these tissues and functions into an integrated multicellular organism yields not only the characteristics of the separate parts and processes but also quite a new set of characteristics which would not have been predictable on the basis of examination of the separate parts."

Growth
A vascular plant begins from a single celled zygote, formed by fertilisation of an egg cell by a sperm cell. From that point, it begins to divide to form a plant embryo through the process of embryogenesis. As this happens, the resulting cells will organize so that one end becomes the first root, while the other end forms the tip of the shoot. In seed plants, the embryo will develop one or more "seed leaves" (cotyledons). By the end of embryogenesis, the young plant will have all the parts necessary to begin its life.

Once the embryo germinates from its seed or parent plant, it begins to produce additional organs (leaves, stems, and roots) through the process of organogenesis. New roots grow from root meristems located at the tip of the root, and new stems and leaves grow from shoot meristems located at the tip of the shoot. Branching occurs when small clumps of cells left behind by the meristem, and which have not yet undergone cellular differentiation to form a specialized tissue, begin to grow as the tip of a new root or shoot. Growth from any such meristem at the tip of a root or shoot is termed primary growth and results in the lengthening of that root or shoot. Secondary growth results in widening of a root or shoot from divisions of cells in a cambium.

In addition to growth by cell division, a plant may grow through cell elongation. This occurs when individual cells or groups of cells grow longer. Not all plant cells will grow to the same length. When cells on one side of a stem grow longer and faster than cells on the other side, the stem will bend to the side of the slower growing cells as a result. This directional growth can occur via a plant's response to a particular stimulus, such as light (phototropism), gravity (gravitropism), water, (hydrotropism), and physical contact (thigmotropism).

Plant growth and development are mediated by specific plant hormones and plant growth regulators (PGRs) (Ross et al. 1983). Endogenous hormone levels are influenced by plant age, cold hardiness, dormancy, and other metabolic conditions; photoperiod, drought, temperature, and other external environmental conditions; and exogenous sources of PGRs, e.g., externally applied and of rhizospheric origin.

Morphological variation
Plants exhibit natural variation in their form and structure. While all organisms vary from individual to individual, plants exhibit an additional type of variation. Within a single individual, parts are repeated which may differ in form and structure from other similar parts. This variation is most easily seen in the leaves of a plant, though other organs such as stems and flowers may show similar variation. There are three primary causes of this variation: positional effects, environmental effects, and juvenility.

Evolution of plant morphology
Transcription factors and transcriptional regulatory networks play key roles in plant morphogenesis and their evolution. During plant landing, many novel transcription factor families emerged and are preferentially wired into the networks of multicellular development, reproduction, and organ development, contributing to more complex morphogenesis of land plants.

Most land plants share a common ancestor, multicellular algae. An example of the evolution of plant morphology is seen in charophytes. Studies have shown that charophytes have traits that are homologous to land plants. There are two main theories of the evolution of plant morphology, these theories are the homologous theory and the antithetic theory. The commonly accepted theory for the evolution of plant morphology is the antithetic theory. The antithetic theory states that the multiple mitotic divisions that take place before meiosis, cause the development of the sporophyte. Then the sporophyte will development as an independent organism.

Developmental model organisms
Much of developmental biology research in recent decades has focused on the use of a small number of model organisms. It has turned out that there is much conservation of developmental mechanisms across the animal kingdom. In early development different vertebrate species all use essentially the same inductive signals and the same genes encoding regional identity. Even invertebrates use a similar repertoire of signals and genes although the body parts formed are significantly different. Model organisms each have some particular experimental advantages which have enabled them to become popular among researchers. In one sense they are "models" for the whole animal kingdom, and in another sense they are "models" for human development, which is difficult to study directly for both ethical and practical reasons. Model organisms have been most useful for elucidating the broad nature of developmental mechanisms. The more detail is sought, the more they differ from each other and from humans.

Plants

 * Thale cress (Arabidopsis thaliana)

Vertebrates

 * Frog: Xenopus (X. laevis and X. tropicalis). Good embryo supply. Especially suitable for microsurgery.
 * Zebrafish: Danio rerio. Good embryo supply. Well developed genetics.
 * Chicken: Gallus gallus. Early stages similar to mammal, but microsurgery easier. Low cost.
 * Mouse: Mus musculus. A mammal with well developed genetics.

Invertebrates

 * Fruit fly: Drosophila melanogaster. Good embryo supply. Well developed genetics.
 * Nematode: Caenorhabditis elegans. Good embryo supply. Well developed genetics. Low cost.

Unicellular

 * Algae: Chlamydomonas
 * Yeast: Saccharomyces

Others
Also popular for some purposes have been sea urchins and ascidians. For studies of regeneration urodele amphibians such as the axolotl Ambystoma mexicanum are used, and also planarian worms such as Schmidtea mediterranea. Organoids have also been demonstrated as an efficient model for development. Plant development has focused on the thale cress Arabidopsis thaliana as a model organism.

title: Developmental biology