Журнал фильтра правок

{{Use dmy dates|date=May 2019|cs1-dates=y}}

{{distinguish|Unicode (telegraphy)}}

{{For|what the term "Unicode" means in Microsoft documentation|UTF-16}}

{{Short description|Character encoding standard}}

{{Infobox character encoding

| name = Unicode

| mime =

| alias = [[Universal Coded Character Set]] (UCS)

| image = New Unicode logo.svg

| caption = Logo of the [[Unicode Consortium]]

| standard = Unicode Standard

| lang = International

| status =

| encodings = [[UTF-8]], [[UTF-16]], [[GB 18030|GB18030]]<br/>'''Less common''': [[UTF-32]], [[BOCU]], [[Standard Compression Scheme for Unicode|SCSU]], [[UTF-7]]

| encodes =

| extends =

| prev = [[ISO 8859]], various others

| next =

}}

{{Contains special characters| special = uncommon [[Unicode]] characters}}

'''Unicode''' is an [[information technology]] [[technical standard|standard]] for the consistent [[character encoding|encoding]], representation, and handling of [[character (computing)|text]] expressed in most of the world's [[writing system]]s. The standard is maintained by the [[Unicode Consortium]], and {{as of|March 2020|lc=y}}, there is a repertoire of {{unicodenover}} (these [[character (computing)|characters]] consist of 143,696 graphic characters and 163 format characters) covering 154 modern and historic [[script (Unicode)|scripts]], as well as multiple symbol sets and [[emoji]]. The character repertoire of the Unicode Standard is synchronized with [[ISO/IEC 10646]], and both are code-for-code identical.

''The Unicode Standard'' consists of a set of code charts for visual reference, an encoding method and set of standard [[character encoding]]s, a set of reference [[data file]]s, and a number of related items, such as character properties, rules for [[Unicode normalization|normalization]], decomposition, [[Unicode collation algorithm|collation]], rendering, and [[bidirectional text]] display order (for the correct display of text containing both right-to-left scripts, such as [[Arabic script|Arabic]] and [[Hebrew alphabet|Hebrew]], and left-to-right scripts).<ref>{{Cite web | title = The Unicode Standard: A Technical Introduction | url = https://www.unicode.org/standard/principles.html | accessdate = 2010-03-16}}</ref>

Unicode's success at unifying character sets has led to its widespread and predominant use in the [[internationalization and localization]] of computer [[software]]. The standard has been implemented in many recent technologies, including modern [[operating system]]s, [[XML]], [[Java (programming language)|Java]] (and other programming languages), and the [[.NET Framework]].

[[Comparison of Unicode encodings|Unicode can be implemented]] by different [[character encoding]]s. The Unicode standard defines [[UTF-8]], [[UTF-16]], and [[UTF-32]], and several other encodings are in use. The most commonly used encodings are UTF-8, UTF-16, and [[Universal Coded Character Set|UCS]]-2 (without full support for Unicode), a precursor of UTF-16; [[GB 18030|GB18030]] is standardized in China and implements Unicode fully, while not an official Unicode standard.

UTF-8, the dominant encoding on the [[World Wide Web]] (used in over 94% of websites {{As of|2019|November|df=|lc=y}}),<ref>{{Cite web|url=https://w3techs.com/technologies/cross/character_encoding/ranking|title=Usage Survey of Character Encodings broken down by Ranking|website=w3techs.com|language=en|access-date=2019-11-11}}</ref> uses one [[byte]]{{efn|The Unicode Consortium uses the ambiguous term byte; The [[International Organization for Standardization]] (ISO), the [[International Electrotechnical Commission]] (IEC) and the [[Internet Engineering Task Force]] (IETF) use the more specific term [[Octet (computing)|octet]] in current documents related to Unicode.|group=note}}for the first 128 [[code point]]s, and up to 4 bytes for other characters.<ref>{{cite web|url=https://www.unicode.org/versions/Unicode13.0.0/ch03.pdf#I1.36559|work=The Unicode Standard|title=Conformance | date=March 2020|accessdate=2020-03-15}}</ref> The first 128 Unicode code points represent the [[ASCII]] characters, which means that any ASCII text is also a UTF-8 text.

UCS-2 uses two bytes (16&nbsp;bits) for each character but can only encode the first 65,536 code points, the so-called [[Basic Multilingual Plane]] (BMP). With 1,112,064 possible Unicode code points corresponding to characters (see [[#Architecture and terminology|below]]) on 17 planes, and with over 143,000 code points defined as of version 13.0, UCS-2 is only able to represent less than half of all encoded Unicode characters. Therefore, UCS-2 is outdated, though still widely used in software. UTF-16 extends UCS-2, by using the same [[16-bit]] encoding as UCS-2 for the Basic Multilingual Plane, and a 4-byte encoding for the other planes. As long as it contains no code points in the reserved range U+D800–U+DFFF, a UCS-2 text is valid UTF-16 text.

UTF-32 (also referred to as UCS-4) uses four bytes for each character. Like UCS-2, the number of bytes per character is fixed, facilitating character indexing; but unlike UCS-2, UTF-32 is able to encode all Unicode code points. However, because each character uses four bytes, UTF-32 takes significantly more space than other encodings, and is not widely used.

==Origin and development==

Unicode has the explicit aim of transcending the limitations of traditional character encodings, such as those defined by the [[ISO/IEC 8859]] standard, which find wide usage in various countries of the world but remain largely incompatible with each other. Many traditional character encodings share a common problem in that they allow bilingual computer processing (usually using [[Latin character]]s and the local script), but not multilingual computer processing (computer processing of arbitrary scripts mixed with each other).

Unicode, in intent, encodes the underlying characters—[[grapheme]]s and grapheme-like units—rather than the variant [[glyph]]s (renderings) for such characters. In the case of [[Chinese characters]], this sometimes leads to controversies over distinguishing the underlying character from its variant glyphs (see [[Han unification]]).

In text processing, Unicode takes the role of providing a unique ''code point''—a [[number]], not a glyph—for each character. In other words, Unicode represents a character in an abstract way and leaves the visual rendering (size, shape, [[font]], or style) to other software, such as a [[web browser]] or [[word processor]]. This simple aim becomes complicated, however, because of concessions made by Unicode's designers in the hope of encouraging a more rapid adoption of Unicode.

The first 256 code points were made identical to the content of [[ISO/IEC 8859-1]] so as to make it trivial to convert existing western text. Many essentially identical characters were encoded multiple times at different code points to preserve distinctions used by legacy encodings and therefore, allow conversion from those encodings to Unicode (and back) without losing any information. For example, the "[[Halfwidth and Fullwidth Forms (Unicode block)|fullwidth forms]]" section of code points encompasses a full duplicate of the Latin alphabet because Chinese, Japanese, and Korean ([[CJK]]) fonts contain two versions of these letters, "fullwidth" matching the width of the CJK characters, and normal width. For other examples, see [[duplicate characters in Unicode]].

==={{anchor|Unicode 88}}History===

Based on experiences with the [[Xerox Character Code Standard]] (XCCS) since 1980,<ref name="unicode-88"/> the origins of Unicode date to 1987, when [[Joe Becker (Unicode)|Joe Becker]] from [[Xerox]] with [[Lee Collins (software engineer)|Lee Collins]] and [[Mark Davis (Unicode)|Mark Davis]] from [[Apple Inc.|Apple]], started investigating the practicalities of creating a universal character set.<ref>{{cite web |title=Summary Narrative |url=https://www.unicode.org/history/summary.html |access-date=2010-03-15}}</ref> With additional input from Peter Fenwick and Dave Opstad,<ref name="unicode-88"/> Joe Becker published a draft proposal for an "international/multilingual text character encoding system in August 1988, tentatively called Unicode". He explained that "[t]he name 'Unicode' is intended to suggest a unique, unified, universal encoding".<ref name="unicode-88">{{Cite web |url=https://unicode.org/history/unicode88.pdf |title=Unicode 88 |author-last=Becker |author-first=Joseph D. |author-link=Joseph D. Becker |date=1998-09-10 |orig-year=1988-08-29 |edition=10th anniversary reprint |website=unicode.org |publisher=[[Unicode Consortium]] |access-date=2016-10-25 |url-status=live |archive-url=https://web.archive.org/web/20161125224409/https://unicode.org/history/unicode88.pdf |archive-date=2016-11-25 |quote=In 1978, the initial proposal for a set of "Universal Signs" was made by [[Bob Belleville]] at [[Xerox PARC]]. Many persons contributed ideas to the development of a new encoding design. Beginning in 1980, these efforts evolved into the [[Xerox Character Code Standard]] (XCCS) by the present author, a multilingual encoding which has been maintained by Xerox as an internal corporate standard since 1982, through the efforts of Ed Smura, Ron Pellar, and others.<br/>Unicode arose as the result of eight years of working experience with XCCS. Its fundamental differences from XCCS were proposed by Peter Fenwick and Dave Opstad (pure 16-bit codes), and by [[Lee Collins (Unicode)|Lee Collins]] (ideographic character unification). Unicode retains the many features of XCCS whose utility have been proved over the years in an international line of communication multilingual system products.}}</ref>

In this document, entitled ''Unicode 88'', Becker outlined a [[16-bit]] character model:<ref name="unicode-88"/>

<blockquote>

Unicode is intended to address the need for a workable, reliable world text encoding. Unicode could be roughly described as "wide-body ASCII" that has been stretched to 16&nbsp;bits to encompass the characters of all the world's living languages. In a properly engineered design, 16&nbsp;bits per character are more than sufficient for this purpose.

</blockquote>

His original 16-bit design was based on the assumption that only those scripts and characters in modern use would need to be encoded:<ref name="unicode-88"/>

<blockquote>

Unicode gives higher priority to ensuring utility for the future than to preserving past antiquities. Unicode aims in the first instance at the characters published in modern text (e.g. in the union of all newspapers and magazines printed in the world in 1988), whose number is undoubtedly far below 2¹⁴ = 16,384. Beyond those modern-use characters, all others may be defined to be obsolete or rare; these are better candidates for private-use registration than for congesting the public list of generally useful Unicodes.

</blockquote>

In early 1989, the Unicode working group expanded to include Ken Whistler and Mike Kernaghan of Metaphor, Karen Smith-Yoshimura and Joan Aliprand of [[Research Libraries Group|RLG]], and Glenn Wright of [[Sun Microsystems]], and in 1990, Michel Suignard and Asmus Freytag from [[Microsoft]] and Rick McGowan of [[NeXT]] joined the group. By the end of 1990, most of the work on mapping existing character encoding standards had been completed, and a final review draft of Unicode was ready.

The [[Unicode Consortium]] was incorporated in California on 3 January 1991,<ref>[https://unicode.org/history/publicationdates.html History of Unicode Release and Publication Dates] on ''unicode.org.'' Retrieved February 28, 2017.</ref> and in October 1991, the first volume of the Unicode standard was published. The second volume, covering Han ideographs, was published in June 1992.

In 1996, a surrogate character mechanism was implemented in Unicode 2.0, so that Unicode was no longer restricted to 16 bits. This increased the Unicode codespace to over a million code points, which allowed for the encoding of many historic scripts (e.g., [[Egyptian hieroglyphs]]) and thousands of rarely used or obsolete characters that had not been anticipated as needing encoding. Among the characters not originally intended for Unicode are rarely used Kanji or Chinese characters, many of which are part of personal and place names, making them rarely used, but much more essential than envisioned in the original architecture of Unicode.<ref name=unicoderevisited>{{cite web|last=Searle|first=Stephen J|title=Unicode Revisited|url=http://tronweb.super-nova.co.jp/unicoderevisited.html|accessdate=2013-01-18}}</ref>

The Microsoft TrueType specification version 1.0 from 1992 used the name ''Apple Unicode'' instead of ''Unicode'' for the Platform ID in the naming table.

===Unicode Consortium===

{{Main|Unicode Consortium}}

The Unicode Consortium is a nonprofit organization that coordinates Unicode's development. Full members include most of the main computer software and hardware companies with any interest in text-processing standards, including [[Adobe Inc.|Adobe]], [[Apple Inc.|Apple]], [[Google]], [[International Business Machines|IBM]], [[Microsoft]], and [[Oracle Corporation]].<ref name="members">{{cite web

| title = The Unicode Consortium Members

| url = https://unicode.org/consortium/members.html

| accessdate = 2019-01-04}}</ref>

Over the years several countries or government agencies have been members of the Unicode Consortium. Presently only the [[Ministry of Endowments and Religious Affairs (Oman)]] is a full member with voting rights.<ref name="members" />

The Consortium has the ambitious goal of eventually replacing existing character encoding schemes with Unicode and its standard [[#Unicode Transformation Format and Universal Character Set|Unicode Transformation Format]] (UTF) schemes, as many of the existing schemes are limited in size and scope and are incompatible with [[multilingualism|multilingual]] environments.

===Scripts covered===

{{Main|Script (Unicode)}}

[[File:Unicode sample.png|thumb|right|200px|Many modern applications can render a substantial subset of the many [[scripts in Unicode]], as demonstrated by this screenshot from the [[OpenOffice.org]] application.]]<!-- screenshot fair use rationale: this screenshot is used specifically to illustrate the Unicode-related capabilities of modern desktop applications and the breadth of supported Unicode scripts -->

Unicode covers almost all scripts ([[writing system]]s) in current use today.<ref>{{cite web

| title = Character Code Charts

| url = https://www.unicode.org/charts/

| accessdate = 2010-03-17}}

</ref>{{failed verification|date=October 2013}}<ref>{{Cite web|url=https://home.unicode.org/basic-info/faq/|title=Unicode FAQ|last=|first=|date=|website=|url-status=live|archive-url=|archive-date=|access-date=2020-04-02}}</ref>

A total of 154 [[Script (Unicode)|scripts]] are included in the latest version of Unicode (covering [[alphabet]]s, [[abugida]]s and [[Syllabary|syllabaries]]), although there are still scripts that are not yet encoded, particularly those mainly used in historical, liturgical, and academic contexts. Further additions of characters to the already encoded scripts, as well as symbols, in particular for mathematics and [[musical notation|music]] (in the form of notes and rhythmic symbols), also occur.

The Unicode Roadmap Committee ([[Michael Everson]], Rick McGowan, Ken Whistler, V.S. Umamaheswaran<ref>{{Cite web | title=Roadmap to the BMP | url=https://www.unicode.org/roadmaps/bmp/ | publisher=[[Unicode Consortium]] | accessdate=30 July 2018 }}</ref>) maintain the list of scripts that are candidates or potential candidates for encoding and their tentative code block assignments on the [https://www.unicode.org/roadmaps/ Unicode Roadmap] page of the [[Unicode Consortium]] Web site. For some scripts on the Roadmap, such as [[Jurchen script|Jurchen]] and [[Khitan small script]], encoding proposals have been made and they are working their way through the approval process. For others scripts, such as [[Maya script|Mayan]] (besides numbers) and [[Rongorongo]], no proposal has yet been made, and they await agreement on character repertoire and other details from the user communities involved.

Some modern invented scripts which have not yet been included in Unicode (e.g., [[Tengwar]]) or which do not qualify for inclusion in Unicode due to lack of real-world use (e.g., [[Klingon scripts|Klingon]]) are listed in the [[ConScript Unicode Registry]], along with unofficial but widely used [[Private Use Areas]] code assignments.

There is also a [[Medieval Unicode Font Initiative]] focused on special Latin medieval characters. Part of these proposals have been already included into Unicode.

The [https://linguistics.berkeley.edu/sei/ Script Encoding Initiative], a project run by Deborah Anderson at the [[University of California, Berkeley]] was founded in 2002 with the goal of funding proposals for scripts not yet encoded in the standard. The project has become a major source of proposed additions to the standard in recent years.<ref>{{cite web|url=https://www.unicode.org/pending/about-sei.html |title=About The Script Encoding Initiative |publisher=The Unicode Consortium |date= |accessdate=2012-06-04}}</ref>

==={{anchor|1.0.0|1.0.1|1.1|2.0|2.1|3.0|3.1|3.2|4.0|4.1|5.0|5.1|5.2|6.0|6.1|6.2|6.3|7.0|8.0|9.0|10.0|11.0|12.0|12.1|13.0|14.0}}Versions===

Unicode is developed in conjunction with the [[International Organization for Standardization]] and shares the character repertoire with [[ISO/IEC 10646]]: the Universal Character Set. Unicode and ISO/IEC 10646 function equivalently as character encodings, but ''The Unicode Standard'' contains much more information for implementers, covering—in depth—topics such as bitwise encoding, [[Unicode collation algorithm|collation]] and rendering. The Unicode Standard enumerates a multitude of character properties, including those needed for supporting [[Bi-directional text|bidirectional text]]. The two standards do use slightly different terminology.

The Unicode Consortium first published ''The Unicode Standard'' in 1991 (version 1.0), and has published new versions on a regular basis since then. The latest version of the Unicode Standard, version 13.0, was released in March 2020, and is available in electronic format from the consortium's website. The last version of the standard that was published completely in book form (including the code charts) was version 5.0 in 2006, but since version 5.2 (2009) the core specification of the standard has been published as a print-on-demand paperback.<ref name=version6.1PoD>{{cite web|title=Unicode 6.1 Paperback Available|url=https://www.unicode.org/mail-arch/unicode-ml/y2012-m05/0240.html|work=announcements_at_unicode.org|accessdate=2012-05-30}}</ref> The entire text of each version of the standard, including the core specification, standard annexes and code charts, is freely available in [[PDF]] format on the Unicode website.

In April 2020, Unicode announced that the release of the forthcoming version 14.0 had been postponed by six months from its initial release of March 2021 due to the [[COVID-19 pandemic]].<ref>{{cite web|title=Unicode 14.0 Delayed for 6 Months|url=https://home.unicode.org/unicode-14-0-delayed-for-6-months/|accessdate=2020-05-05}}</ref>

Thus far, the following major and minor versions of the Unicode standard have been published. Update versions, which do not include any changes to character repertoire, are signified by the third number (e.g., "version 4.0.1") and are omitted in the table below.<ref>{{cite web | title = Enumerated Versions of The Unicode Standard | url = https://www.unicode.org/versions/enumeratedversions.html | accessdate = 2016-06-21}}</ref>

|+ Unicode versions

|-

!rowspan=2| Version

!rowspan=2| Date

!rowspan=2| Book

!rowspan=2| Corresponding [[Universal Character Set|ISO/IEC 10646]] edition

!rowspan=2| [[Script (Unicode)|Scripts]]

!colspan=2| Characters

! Total{{refn|The number of characters listed for each version of Unicode is the total number of graphic and format characters (i.e., excluding [[Private Use Area|private-use characters]], [[Unicode control characters|control characters]], [[noncharacter|noncharacters]] and [[surrogate code points]]).|group=tablenote}}

! Notable additions

| 1.0.0

| October 1991

| {{ISBN|0-201-56788-1}} (Vol. 1)

| 24

| 7,129

| Initial repertoire covers these scripts: [[Arabic script|Arabic]], [[Armenian alphabet|Armenian]], [[Bengali alphabet|Bengali]], [[Zhuyin|Bopomofo]], [[Cyrillic script|Cyrillic]], [[Devanagari]], [[Georgian alphabet|Georgian]], [[Greek alphabet|Greek and Coptic]], [[Gujarati alphabet|Gujarati]], [[Gurmukhi script|Gurmukhi]], [[Hangul]], [[Hebrew alphabet|Hebrew]], [[Hiragana]], [[Kannada alphabet|Kannada]], [[Katakana]], [[Lao script|Lao]], [[Latin script|Latin]], [[Malayalam script|Malayalam]], [[Oriya script|Oriya]], [[Tamil script|Tamil]], [[Telugu script|Telugu]], [[Thai alphabet|Thai]], and [[Tibetan script|Tibetan]].<ref>{{cite web| title = Unicode Data 1.0.0|url= https://www.unicode.org/Public/reconstructed/1.0.0/UnicodeData.txt| accessdate = 2010-03-16}}</ref>

| June 1992

| {{ISBN|0-201-60845-6}} (Vol. 2)

| 25

| 28,327<br />(21,204 added; 6 removed)

| The initial set of 20,902 [[CJK Unified Ideographs]] is defined.<ref>

{{cite web

| url = https://www.unicode.org/Public/reconstructed/1.0.1/UnicodeData.txt

| accessdate = 2010-03-16}}</ref>

| 1.1

| June 1993

| 24

| 34,168<br />(5,963 added; 89 removed; 33 reclassified as control characters)

| 4,306 more [[Hangul]] syllables added to original set of 2,350 characters. [[Tibetan script|Tibetan]] removed.<ref>{{cite web

| url = https://www.unicode.org/Public/1.1-Update/UnicodeData-1.1.5.txt

| accessdate = 2010-03-16 }}

</ref>

| 2.0

| July 1996

| {{ISBN|0-201-48345-9}}

| ISO/IEC 10646-1:1993 plus Amendments 5, 6 and 7

| 25

| 38,885<br />(11,373 added; 6,656 removed)

| Original set of [[Hangul]] syllables removed, and a new set of 11,172 Hangul syllables added at a new location. [[Tibetan script|Tibetan]] added back in a new location and with a different character repertoire. Surrogate character mechanism defined, and Plane 15 and Plane 16 [[Private use (Unicode)|Private Use Areas]] allocated.<ref>{{cite web

| title = Unicode Data-2.0.14

| url = https://www.unicode.org/Public/2.0-Update/UnicodeData-2.0.14.txt

| accessdate = 2010-03-16}}

</ref>

| 2.1

| May 1998

| ISO/IEC 10646-1:1993 plus Amendments 5, 6 and 7, as well as two characters from Amendment 18

| 38,887<br />(2 added)

| [[Euro sign]] and [[Specials (Unicode block)|Object Replacement Character]] added.<ref>{{cite web

| title = Unicode Data-2.1.2

| url = https://www.unicode.org/Public/2.1-Update/UnicodeData-2.1.2.txt

| accessdate = 2010-03-16}}

</ref>

| 3.0

| September 1999

| {{ISBN|0-201-61633-5}}

| 38

| 49,194<br />(10,307 added)

| [[Cherokee syllabary|Cherokee]], [[Ge'ez alphabet|Ethiopic]], [[Khmer script|Khmer]], [[Mongolian script|Mongolian]], [[Burmese script|Burmese]], [[Ogham]], [[Runic alphabet|Runic]], [[Sinhala script|Sinhala]], [[Syriac alphabet|Syriac]], [[Tāna|Thaana]], [[Canadian Aboriginal syllabics|Unified Canadian Aboriginal Syllabics]], and [[Yi script|Yi Syllables]] added, as well as a set of [[Braille]] patterns.<ref>{{cite web

| title = Unicode Data-3.0.0

| url = https://www.unicode.org/Public/3.0-Update/UnicodeData-3.0.0.txt

| accessdate = 2010-03-16}}

</ref>

| 3.1

| March 2001

| 41

| 94,140<br />(44,946 added)

| [[Deseret alphabet|Deseret]], [[Gothic alphabet|Gothic]] and [[Old Italic alphabet|Old Italic]] added, as well as sets of symbols for [[Modern musical symbols|Western music]] and [[Byzantine music]], and 42,711 additional [[CJK Unified Ideographs]].<ref>{{cite web

| title =Unicode Data-3.1.0

| url =https://www.unicode.org/Public/3.1-Update/UnicodeData-3.1.0.txt

| accessdate = 2010-03-16 }}

</ref>

| 3.2

| March 2002

| ISO/IEC 10646-1:2000 plus Amendment 1

| 45

| 95,156<br />(1,016 added)

| [[Philippines|Philippine]] scripts [[Buhid script|Buhid]], [[Hanunó'o script|Hanunó'o]], [[Baybayin|Tagalog]], and [[Tagbanwa script|Tagbanwa]] added.<ref>{{cite web

| title = Unicode Data-3.2.0

| url = https://www.unicode.org/Public/3.2-Update/UnicodeData-3.2.0.txt

| accessdate = 2010-03-16}}

</ref>

| 4.0

| April 2003

| {{ISBN|0-321-18578-1}}

| 52

| 96,382<br />(1,226 added)

| [[Cypriot syllabary]], [[Limbu script|Limbu]], [[Linear B]], [[Osmanya script|Osmanya]], [[Shavian alphabet|Shavian]], [[Tai Nüa language#Writing system|Tai Le]], and [[Ugaritic alphabet|Ugaritic]] added, as well as [[Hexagram (I Ching)|Hexagram symbols]].<ref>{{cite web

| title = Unicode Data-4.0.0

| url = https://www.unicode.org/Public/4.0-Update/UnicodeData-4.0.0.txt

| accessdate = 2010-03-16}}

</ref>

| 4.1

| March 2005

| ISO/IEC 10646:2003 plus Amendment 1

| 59

| 97,655<br />(1,273 added)

| [[Lontara alphabet|Buginese]], [[Glagolitic alphabet|Glagolitic]], [[Kharoṣṭhī|Kharoshthi]], [[New Tai Lue alphabet|New Tai Lue]], [[Old Persian cuneiform script|Old Persian]], [[Sylheti Nagari|Syloti Nagri]], and [[Tifinagh]] added, and [[Coptic alphabet|Coptic]] was disunified from [[Greek alphabet|Greek]]. Ancient [[Unicode numerals#Ancient Greek numerals|Greek numbers]] and [[Musical notation#Ancient Greece|musical symbols]] were also added.<ref>{{cite web|url=https://www.unicode.org/Public/4.1.0/ucd/UnicodeData.txt|title=Unicode Data-4.1.0|accessdate=2010-03-16}}

</ref>

| 5.0

| July 2006

| {{ISBN|0-321-48091-0}}

| ISO/IEC 10646:2003 plus Amendments 1 and 2, as well as four characters from Amendment 3

| 64

| 99,024<br />(1,369 added)

| [[Balinese alphabet|Balinese]], [[Cuneiform]], [[N'Ko alphabet|N'Ko]], [[Phags-pa script|Phags-pa]], and [[Phoenician alphabet|Phoenician]] added.<ref>{{cite web

| url = https://www.unicode.org/Public/5.0.0/ucd/UnicodeData.txt

| accessdate = 2010-03-17}}

</ref>

| 5.1

| April 2008

| ISO/IEC 10646:2003 plus Amendments 1, 2, 3 and 4

| 75

| 100,648<br />(1,624 added)

| [[Carian script|Carian]], [[Cham alphabet|Cham]], [[Kayah Li script|Kayah Li]], [[Lepcha script|Lepcha]], [[Lycian script|Lycian]], [[Lydian script|Lydian]], [[Ol Chiki script|Ol Chiki]], [[Rejang script|Rejang]], [[Saurashtra script|Saurashtra]], [[Sundanese script|Sundanese]], and [[Vai syllabary|Vai]] added, as well as sets of symbols for the [[Phaistos Disc]], [[Mahjong|Mahjong tiles]], and [[Dominoes|Domino tiles]]. There were also important additions for [[Burmese script|Burmese]], additions of letters and [[Scribal abbreviation]]s used in medieval [[manuscript]]s, and the addition of [[Capital ẞ]].<ref>{{cite web

| url = https://www.unicode.org/Public/5.1.0/ucd/UnicodeData.txt

| accessdate = 2010-03-17 }}

</ref>

| 5.2

| October 2009

| {{ISBN|978-1-936213-00-9}}

| ISO/IEC 10646:2003 plus Amendments 1, 2, 3, 4, 5 and 6

| 90

| 107,296<br />(6,648 added)

| [[Avestan alphabet|Avestan]], [[Bamum script|Bamum]], [[Egyptian hieroglyphs]] (the [[Gardiner's sign list|Gardiner Set]], comprising 1,071 characters), [[Imperial Aramaic]], [[Inscriptional Pahlavi]], [[Inscriptional Parthian]], [[Javanese script|Javanese]], [[Kaithi]], [[Fraser alphabet|Lisu]], [[Meitei Mayek script|Meetei Mayek]], [[South Arabian alphabet|Old South Arabian]], [[Old Turkic script|Old Turkic]], [[Samaritan script|Samaritan]], [[Tai Tham script|Tai Tham]] and [[Tai Viet script|Tai Viet]] added. 4,149 additional [[CJK Unified Ideographs]] (CJK-C), as well as extended Jamo for [[Hangul|Old Hangul]], and characters for [[Vedic Sanskrit]].<ref>{{cite web

| url = https://www.unicode.org/Public/5.2.0/ucd/UnicodeData.txt

| accessdate = 2010-03-17}}

</ref>

| 6.0

| October 2010

| {{ISBN|978-1-936213-01-6}}

| ISO/IEC 10646:2010 plus the [[Indian rupee sign]]

| 93

| 109,384<br />(2,088 added)

| [[Batak alphabet|Batak]], [[Brāhmī script|Brahmi]], [[Mandaic alphabet|Mandaic]], [[playing card]] symbols, [[Traffic sign|transport]] and [[map]] symbols, [[alchemical symbol]]s, [[emoticons]] and [[emoji]]. 222 additional [[CJK Unified Ideographs]] (CJK-D) added.<ref>{{cite web

| url = https://www.unicode.org/Public/6.0.0/ucd/UnicodeData.txt

| accessdate = 2010-10-11}}

</ref>

| 6.1

| January 2012

| {{ISBN|978-1-936213-02-3}}

| 100

| 110,116<br />(732 added)

| [[Chakma alphabet|Chakma]], [[Meroitic alphabet|Meroitic cursive]], [[Meroitic alphabet|Meroitic hieroglyphs]], [[Pollard script|Miao]], [[Śāradā script|Sharada]], [[Sora Sompeng]], and [[Takri alphabet|Takri]].<ref>{{cite web

| url = https://www.unicode.org/Public/6.1.0/ucd/UnicodeData.txt

| accessdate = 2012-01-31}}

</ref>

| 6.2

| September 2012

| {{ISBN|978-1-936213-07-8}}

| ISO/IEC 10646:2012 plus the [[Turkish lira sign]]

| 100

| 110,117<br />(1 added)

| [[Turkish lira sign]].<ref>{{cite web

| url = https://www.unicode.org/Public/6.2.0/ucd/UnicodeData.txt

| accessdate = 2012-09-26}}

</ref>

| 6.3

| September 2013

| {{ISBN|978-1-936213-08-5}}

| ISO/IEC 10646:2012 plus six characters

| 100

| 110,122<br />(5 added)

| 5 bidirectional formatting characters.<ref>{{cite web

| url = https://www.unicode.org/Public/6.3.0/ucd/UnicodeData.txt

| accessdate = 2013-09-30}}

</ref>

| 7.0

| June 2014

| {{ISBN|978-1-936213-09-2}}

| ISO/IEC 10646:2012 plus Amendments 1 and 2, as well as the [[Ruble sign]]

| 123

| 112,956<br />(2,834 added)

| [[Bassa alphabet|Bassa Vah]], [[Caucasian Albanian alphabet|Caucasian Albanian]], [[Duployan shorthand|Duployan]], [[Elbasan alphabet|Elbasan]], [[Grantha alphabet|Grantha]], [[Khojki]], [[Khudabadi alphabet|Khudawadi]], [[Linear A]], [[Mahajani]], [[Manichaean alphabet|Manichaean]], [[Mende script|Mende Kikakui]], [[Modi alphabet|Modi]], [[Mro script|Mro]], [[Nabataean alphabet|Nabataean]], [[Old North Arabian]], [[Old Permic alphabet|Old Permic]], [[Pahawh Hmong]], [[Palmyrene script|Palmyrene]], [[Pau Cin Hau script|Pau Cin Hau]], [[Psalter Pahlavi]], [[Siddhaṃ alphabet|Siddham]], [[Tirhuta]], [[Warang Citi]], and [[Dingbat]]s.<ref>{{cite web

| url = https://www.unicode.org/Public/7.0.0/ucd/UnicodeData.txt

| accessdate = 2014-06-15}}

</ref>

| 8.0

| June 2015

| {{ISBN|978-1-936213-10-8}}

| ISO/IEC 10646:2014 plus Amendment 1, as well as the [[Georgian lari|Lari sign]], nine CJK unified ideographs, and 41 emoji characters<ref>{{Cite web | title=Unicode 8.0.0 | url=https://www.unicode.org/versions/Unicode8.0.0/ | publisher=Unicode Consortium | accessdate=2015-06-17 }}</ref>

| 129

| 120,672<br />(7,716 added)

| [[Ahom alphabet|Ahom]], [[Anatolian hieroglyphs]], [[Hatran alphabet|Hatran]], [[Multani alphabet|Multani]], [[Old Hungarian alphabet|Old Hungarian]], [[SignWriting]], 5,771 [[CJK Unified Ideographs|CJK unified ideographs]], a set of lowercase letters for [[Cherokee syllabary|Cherokee]], and five emoji [[Fitzpatrick scale|skin tone]] modifiers<ref>{{cite web

| url = https://www.unicode.org/Public/8.0.0/ucd/UnicodeData.txt

| accessdate = 2015-06-17}}

</ref>

| 9.0

| June 2016

| {{ISBN|978-1-936213-13-9}}

| ISO/IEC 10646:2014 plus Amendments 1 and 2, as well as Adlam, Newa, Japanese TV symbols, and 74 emoji and symbols<ref>{{Cite web | title=Unicode 9.0.0 | url=https://www.unicode.org/versions/Unicode9.0.0/ | publisher=Unicode Consortium | accessdate=2016-06-21 }}</ref>

| 135

| 128,172<br />(7,500 added)

| [[Adlam script|Adlam]], [[Bhaiksuki alphabet|Bhaiksuki]], [[Zhang-Zhung language#Scripts|Marchen]], [[Prachalit Nepal alphabet|Newa]], [[Osage alphabet|Osage]], [[Tangut script|Tangut]], and 72 [[emoji]]<ref>{{cite web

| url = https://www.unicode.org/Public/9.0.0/ucd/UnicodeData.txt

| accessdate = 2016-06-21}}

</ref><ref name=laobo>{{cite web|first=Martim|last=Lobao|url=https://www.androidpolice.com/2016/06/07/two-emoji-werent-approved-unicode-9-google-added-android-anyway/ |title=These Are The Two Emoji That Weren't Approved For Unicode 9 But Which Google Added To Android Anyway|website=Android Police|date= 7 June 2016|accessdate=4 September 2016}}</ref>

| 10.0

| June 2017

| {{ISBN|978-1-936213-16-0}}

| ISO/IEC 10646:2017 plus 56 [[emoji]] characters, 285 [[hentaigana]] characters, and 3 Zanabazar Square characters<ref>{{Cite web | title=Unicode 10.0.0 | url=https://www.unicode.org/versions/Unicode10.0.0/ | publisher=Unicode Consortium | accessdate=2017-06-20 }}</ref>

| 139

| 136,690<br />(8,518 added)

| [[Zanabazar Square alphabet|Zanabazar Square]], [[Soyombo alphabet|Soyombo]], [[Masaram Gondi script|Masaram Gondi]], [[Nüshu script|Nüshu]], [[hentaigana]] (non-standard [[hiragana]]), 7,494 [[CJK Unified Ideographs|CJK unified ideographs]], and 56 [[emoji]]

| June 2018

| {{ISBN|978-1-936213-19-1}}

| ISO/IEC 10646:2017 plus Amendment 1, as well as 46 Mtavruli Georgian capital letters, 5 CJK unified ideographs, and 66 emoji characters.<ref>{{Cite web | title=The Unicode Standard, Version 11.0.0 Appendix C | url=https://www.unicode.org/versions/Unicode11.0.0/appC.pdf | publisher=Unicode Consortium | accessdate=2018-06-11 }}</ref>

| 137,374<br />(684 added)

| [[Dogri script|Dogra]], [[Georgian scripts#Mkhedruli|Georgian Mtavruli]] capital letters, [[Gunjala Gondi Lipi|Gunjala Gondi]], [[Hanifi Rohingya script|Hanifi Rohingya]], [[Indic Siyaq Numbers (Unicode block)|Indic Siyaq numbers]], [[Makassarese language|Makasar]], [[Medefaidrin]], [[Sogdian alphabet|Old Sogdian and Sogdian]], [[Mayan numerals]], 5 urgently needed [[CJK Unified Ideographs|CJK unified ideographs]], symbols for [[xiangqi]] (Chinese chess) and [[Star (classification)|star ratings]], and 145 [[emoji]]<ref>{{Cite web|url=http://blog.unicode.org/2018/06/announcing-unicode-standard-version-110.html|title=Announcing The Unicode Standard, Version 11.0|website=blog.unicode.org|access-date=2018-06-06}}</ref>

| 12.0

| March 2019

| {{ISBN|978-1-936213-22-1}}

| ISO/IEC 10646:2017 plus Amendments 1 and 2, as well as 62 additional characters.<ref>{{Cite web | title=The Unicode Standard, Version 12.0.0 Appendix C | url=https://www.unicode.org/versions/Unicode12.0.0/appC.pdf | publisher=Unicode Consortium | accessdate=2019-03-05 }}</ref>

| 150

| 137,928<br />(554 added)

| [[Elymaic]], [[Nandinagari]], [[Nyiakeng Puachue Hmong]], [[Wancho script|Wancho]], [[Pollard script|Miao script]] additions for several Miao and Yi dialects in China, [[hiragana]] and [[katakana]] small letters for writing archaic Japanese, [[Tamil script|Tamil]] historic fractions and symbols, [[Lao alphabet|Lao]] letters for [[Pali]], Latin letters for Egyptological and Ugaritic transliteration, hieroglyph format controls, and 61 [[emoji]]<ref>{{Cite web|url=http://blog.unicode.org/2019/03/announcing-unicode-standard-version-120.html|title=Announcing The Unicode Standard, Version 12.0|website=blog.unicode.org|access-date=2019-03-05}}</ref>

| 12.1

| May 2019

| {{ISBN|978-1-936213-25-2}}

| 150

| 137,929<br />(1 added)

| Adds a single character at U+32FF for the square ligature form of the name of the [[Reiwa|Reiwa era]].<ref>{{Cite web|url=http://blog.unicode.org/2019/05/unicode-12-1-en.html|title=Unicode Version 12.1 released in support of the Reiwa Era|website=blog.unicode.org|access-date=2019-05-07}}</ref>

| [http://www.unicode.org/versions/Unicode13.0.0/ 13.0]

| March 2020

| {{ISBN|978-1-936213-26-9}}

| ISO/IEC 10646:2020<ref>{{Cite web | title=The Unicode Standard, Version 13.0– Core Specification Appendix C | url=https://www.unicode.org/versions/Unicode13.0.0/appC.pdf | publisher=Unicode Consortium | accessdate=2020-03-11 }}</ref>

| 154

| 143,859<br />(5,930 added)

| [[Khwarezmian_language#Writing_system|Chorasmian]], [[Dhives akuru|Dives Akuru]], [[Khitan small script]], [[Kurdish alphabets#Yezidi|Yezidi]], 4,969 CJK unified ideographs added (including 4,939 in [[CJK Unified Ideographs Extension G|Ext. G]]), Arabic script additions used to write [[Hausa language|Hausa]], [[Wolof language|Wolof]], and other languages in Africa and other additions used to write [[Hindko]] and [[Punjabi language|Punjabi]] in Pakistan, Bopomofo additions used for Cantonese, Creative Commons license symbols, graphic characters for compatibility with teletext and home computer systems from the 1970s and 1980s, and 55 emoji<ref>{{Cite web|url=http://blog.unicode.org/2020/03/announcing-unicode-standard-version-130.html|title=Announcing The Unicode Standard, Version 13.0|website=blog.unicode.org|access-date=2020-03-11}}</ref>

{{Reflist|group=tablenote}}

==<span id="Upluslink"></span><span id="codespace"></span> Architecture and terminology==

{{See also|Universal Character Set characters}}<!-- Template:U+ links to this paragraph -->

The Unicode Standard defines a ''codespace''<ref name="Glossary">{{cite web|title = Glossary of Unicode Terms|url=https://unicode.org/glossary/|accessdate=2010-03-16}}</ref> of numerical values ranging from 0 through 10FFFF_{[[hexadecimal|16]]},<ref>{{cite book|title=The Unicode Standard, Version 13.0 |url=https://www.unicode.org/versions/Unicode13.0.0/ch03.pdf#G2212|year=2019|page=19|chapter=3.4 Characters and Encoding}}</ref> called ''[[code point|code points]]''<ref name=":0">{{Cite book|url=http://www.unicode.org/versions/Unicode12.0.0/ch02.pdf#G25564|title=The Unicode Standard Version 12.0 – Core Specification|last=|first=|publisher=|year=2019|isbn=|location=|page=29|chapter=2.4 Code Points and Characters}}</ref> and denoted as U+0000 through U+10FFFF ("U+" plus the code point value in [[hexadecimal]], prepended with [[leading zero|leading zeros]] as necessary to result in a minimum of four digits, ''e.&nbsp;g.'', U+00F7 for the division sign, ÷, versus U+13254 for the [[Egyptian hieroglyph]] designating a [[List of hieroglyphs#O|reed shelter]] or a [[c:Category:Winding wall (h hieroglyph)|winding wall]] {{nowrap|( [[File:Hiero O4.png|text-bottom|15px]] )}}<ref>{{Cite web|url=https://www.unicode.org/versions/Unicode13.0.0/appA.pdf|date=March 2020|title=Appendix A: Notational Conventions|publisher=Unicode Consortium|work=The Unicode Standard}} In conformity with the bullet point relating to Unicode in [[MOS:ALLCAPS]], the formal Unicode names are not used in this paragraph.</ref>), respectively. Out of these 2¹⁶ + 2²⁰ defined code points, the code points from U+D800 through U+DFFF, which are used to encode surrogate pairs in [[UTF-16]], are reserved by the Standard and may not be used to encode valid characters, resulting in a net total of 2¹⁶ &minus; 2¹¹ + 2²⁰ = 1,112,064 possible code points corresponding to valid Unicode characters. Not all of these code points necessarily correspond to visible characters; several, for example, are assigned to control codes such as [[carriage return]].

===Code point planes and blocks===

{{Main|Plane (Unicode)}}

The Unicode codespace is divided into seventeen ''planes'', numbered 0 to 16:

{{Planes (Unicode)}}

All code points in the BMP are accessed as a single code unit in [[UTF-16]] encoding and can be encoded in one, two or three bytes in [[UTF-8]]. Code points in Planes 1 through 16 (''supplementary planes'') are accessed as surrogate pairs in UTF-16 and encoded in four bytes in UTF-8.

Within each plane, characters are allocated within named ''[[Block (Unicode)|blocks]]'' of related characters. Although blocks are an arbitrary size, they are always a multiple of 16 code points and often a multiple of 128 code points. Characters required for a given script may be spread out over several different blocks.

===General Category property===

Each code point has a single [[Character property (Unicode)#General Category|General Category]] property. The major categories are denoted: Letter, Mark, Number, Punctuation, Symbol, Separator and Other. Within these categories, there are subdivisions. In most cases other properties must be used to sufficiently specify the characteristics of a code point. The possible General Categories are:

{{General Category (Unicode)}}

Code points in the range U+D800–U+DBFF (1,024 code points) are known as high-'''surrogate''' code points, and code points in the range U+DC00–U+DFFF (1,024 code points) are known as low-surrogate code points. A high-surrogate code point followed by a low-surrogate code point form a surrogate pair in [[UTF-16]] to represent code points greater than U+FFFF. These code points otherwise cannot be used (this rule is ignored often in practice especially when not using UTF-16).

A small set of code points are guaranteed never to be used for encoding characters, although applications may make use of these code points internally if they wish. There are sixty-six of these '''noncharacters''': U+FDD0–U+FDEF and any code point ending in the value FFFE or FFFF (i.e., U+FFFE, U+FFFF, U+1FFFE, U+1FFFF, ... U+10FFFE, U+10FFFF). The set of noncharacters is stable, and no new noncharacters will ever be defined.<ref name="stability-policy">{{cite web

| title = Unicode Character Encoding Stability Policy

| url = https://unicode.org/policies/stability_policy.html

| accessdate = 2010-03-16}}

</ref> Like surrogates, the rule that these cannot be used is often ignored, although the operation of the [[byte order mark]] assumes that U+FFFE will never be the first code point in a text.

Excluding surrogates and noncharacters leaves 1,111,998 code points available for use.

'''Private-use''' code points are considered to be assigned characters, but they have no interpretation specified by the Unicode standard<ref>{{cite web

| title = Properties

| url = https://www.unicode.org/versions/Unicode13.0.0/ch03.pdf#G43463

| accessdate = 2020-03-15 }}

</ref> so any interchange of such characters requires an agreement between sender and receiver on their interpretation. There are three private-use areas in the Unicode codespace:

* Private Use Area: U+E000–U+F8FF (6,400 characters)

* Supplementary Private Use Area-A: U+F0000–U+FFFFD (65,534 characters)

* Supplementary Private Use Area-B: U+100000–U+10FFFD (65,534 characters).

Graphic characters are characters defined by Unicode to have particular semantics, and either have a visible [[glyph]] shape or represent a visible space. As of Unicode 13.0 there are 143,696 graphic characters.

'''Format''' characters are characters that do not have a visible appearance, but may have an effect on the appearance or behavior of neighboring characters. For example, {{unichar|200C|Zero-width non-joiner|nlink=}} and {{unichar|200D|Zero-width joiner|nlink=}} may be used to change the default shaping behavior of adjacent characters (e.g., to inhibit ligatures or request ligature formation). There are 163 format characters in Unicode 13.0.

Sixty-five code points (U+0000–U+001F and U+007F–U+009F) are reserved as '''control''' codes, and correspond to the [[C0 and C1 control codes]] defined in [[ISO/IEC 6429]]. U+0009 (Tab), U+000A (Line Feed), and U+000D (Carriage Return) are widely used in Unicode-encoded texts. In practice the C1 code points are often improperly-translated ([[Mojibake]]) legacy [[Windows-1252]] characters used by some English and Western European texts with Windows technologies.

Graphic characters, format characters, control code characters, and private use characters are known collectively as ''assigned characters''. '''Reserved''' code points are those code points which are available for use, but are not yet assigned. As of Unicode 13.0 there are 830,606 reserved code points.

===Abstract characters===

The set of graphic and format characters defined by Unicode does not correspond directly to the repertoire of ''abstract characters'' that is representable under Unicode. Unicode encodes characters by associating an abstract character with a particular code point.<ref>{{cite web

| title = Unicode Character Encoding Model

| url = https://unicode.org/reports/tr17/

| accessdate = 2010-03-16}}

</ref> However, not all abstract characters are encoded as a single Unicode character, and some abstract characters may be represented in Unicode by a sequence of two or more characters. For example, a Latin small letter "i" with an [[ogonek]], a [[dot above]], and an [[acute accent]], which is required in [[Lithuanian language|Lithuanian]], is represented by the character sequence U+012F, U+0307, U+0301. Unicode maintains a list of uniquely named character sequences for abstract characters that are not directly encoded in Unicode.<ref>{{cite web

| title = Unicode Named Sequences

| url = https://unicode.org/Public/UNIDATA/NamedSequences.txt

| accessdate = 2010-03-16}}

</ref>

All graphic, format, and private use characters have a unique and immutable name by which they may be identified. This immutability has been guaranteed since Unicode version 2.0 by the Name Stability policy.<ref name="stability-policy" /> In cases where the name is seriously defective and misleading, or has a serious typographical error, a formal alias may be defined, and applications are encouraged to use the formal alias in place of the official character name. For example, {{unichar|A015|YI SYLLABLE WU}} has the formal alias {{sc2|YI SYLLABLE ITERATION MARK}}, and {{unichar|FE18|PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRA'''KC'''ET|note=[[sic]]}} has the formal alias {{sc2|PRESENTATION FORM FOR VERTICAL RIGHT WHITE LENTICULAR BRA'''CK'''ET}}.<ref>{{cite web

| title = Unicode Name Aliases

| url = https://unicode.org/Public/UNIDATA/NameAliases.txt

| accessdate = 2010-03-16}}</ref>

===Ready-made versus composite characters===

Unicode includes a mechanism for modifying characters that greatly extends the supported glyph repertoire. This covers the use of [[combining diacritical mark]]s that may be added after the base character by the user. Multiple combining diacritics may be simultaneously applied to the same character. Unicode also contains [[precomposed character|precomposed]] versions of most letter/diacritic combinations in normal use. These make conversion to and from legacy encodings simpler, and allow applications to use Unicode as an internal text format without having to implement combining characters. For example, ''é'' can be represented in Unicode as [[#Upluslink|U+]]0065 ({{sc2|LATIN SMALL LETTER E}}) followed by U+0301 ({{sc2|COMBINING ACUTE ACCENT}}), but it can also be represented as the precomposed character U+00E9 ({{sc2|LATIN SMALL LETTER E WITH ACUTE}}). Thus, in many cases, users have multiple ways of encoding the same character. To deal with this, Unicode provides the mechanism of [[canonical equivalence]].

An example of this arises with [[Hangul]], the Korean alphabet. Unicode provides a mechanism for composing Hangul syllables with their individual subcomponents, known as [[Hangul Jamo]]. However, it also provides 11,172 combinations of precomposed syllables made from the most common jamo.

The [[CJK]] characters currently have codes only for their precomposed form. Still, most of those characters comprise simpler elements (called [[Radical_(Chinese_characters)|radicals]]), so in principle Unicode could have decomposed them as it did with Hangul. This would have greatly reduced the number of required code points, while allowing the display of virtually every conceivable character (which might do away with some of the problems caused by [[Han unification]]). A similar idea is used by some [[input method]]s, such as [[Cangjie method|Cangjie]] and [[Wubi method|Wubi]]. However, attempts to do this for character encoding have stumbled over the fact that Chinese characters do not decompose as simply or as regularly as Hangul does.

A set of [[Radical (Chinese character)|radicals]] was provided in Unicode 3.0 (CJK radicals between U+2E80 and U+2EFF, KangXi radicals in U+2F00 to U+2FDF, and ideographic description characters from U+2FF0 to U+2FFB), but the Unicode standard (ch. 12.2 of Unicode 5.2) warns against using [[Ideographic Description Sequences|ideographic description sequences]] as an alternate representation for previously encoded characters:

{{quote|This process is different from a formal ''encoding'' of an ideograph. There is no canonical description of unencoded ideographs; there is no semantic assigned to described ideographs; there is no equivalence defined for described ideographs. Conceptually, ideographic descriptions are more akin to the English phrase "an 'e' with an acute accent on it" than to the character sequence &lt;U+0065, U+0301&gt;.}}

===Ligatures===

Many scripts, including [[Arabic script|Arabic]] and [[Devanagari|Devanāgarī]], have special orthographic rules that require certain combinations of letterforms to be combined into special [[ligature (typography)|ligature forms]]. The rules governing ligature formation can be quite complex, requiring special script-shaping technologies such as ACE (Arabic Calligraphic Engine by DecoType in the 1980s and used to generate all the Arabic examples in the printed editions of the Unicode Standard), which became the [[proof of concept]] for [[OpenType]] (by Adobe and Microsoft), [[Graphite (SIL)|Graphite]] (by [[SIL International]]), or [[Apple Advanced Typography|AAT]] (by Apple).

Instructions are also embedded in fonts to tell the [[operating system]] how to properly output different character sequences. A simple solution to the placement of combining marks or diacritics is assigning the marks a width of zero and placing the glyph itself to the left or right of the left sidebearing (depending on the direction of the script they are intended to be used with). A mark handled this way will appear over whatever character precedes it, but will not adjust its position relative to the width or height of the base glyph; it may be visually awkward and it may overlap some glyphs. Real stacking is impossible, but can be approximated in limited cases (for example, Thai top-combining vowels and tone marks can just be at different heights to start with). Generally this approach is only effective in monospaced fonts, but may be used as a fallback rendering method when more complex methods fail.

===Standardized subsets===

Several subsets of Unicode are standardized: Microsoft Windows since [[Windows NT 4.0]] supports [[WGL-4]] with 656 characters, which is considered to support all contemporary European languages using the Latin, Greek, or Cyrillic script. Other standardized subsets of Unicode include the Multilingual European Subsets:<ref>[https://www.evertype.com/standards/iso10646/pdf/cwa13873.pdf CWA 13873:2000&nbsp;– Multilingual European Subsets in ISO/IEC 10646-1] [[European Committee for Standardization|CEN]] Workshop Agreement 13873</ref>

MES-1 (Latin scripts only, 335 characters), MES-2 (Latin, Greek and Cyrillic 1062 characters)<ref>[https://www.cl.cam.ac.uk/~mgk25/ucs/mes-2-rationale.html Multilingual European Character Set 2 (MES-2) Rationale], [[Markus Kuhn (computer scientist)|Markus Kuhn]], 1998</ref> and MES-3A & MES-3B (two larger subsets, not shown here). Note that MES-2 includes every character in MES-1 and WGL-4.

{| class="wikitable"

|+ {{nobold|'''WGL-4''', ''MES-1'' and MES-2}}

! Row !! Cells !! Range(s)

!rowspan="2"| 00

| '''''20–7E'''''

| [[Basic Latin (Unicode block)|Basic Latin]] (00–7F)

| '''''A0–FF'''''

| [[Latin-1 Supplement (Unicode block)|Latin-1 Supplement]] (80–FF)

!rowspan="2"| 01

| '''''00–13,'' 14–15, ''16–2B,'' 2C–2D, ''2E–4D,'' 4E–4F, ''50–7E,'' 7F'''

| [[Latin Extended-A]] (00–7F)

| 8F, '''92,''' B7, DE-EF, '''FA–FF'''

| [[Latin Extended-B]] (80–FF <span title="U+024F">...</span>)

!rowspan="3"| 02

| 18–1B, 1E–1F

| Latin Extended-B (<span title="U+00180">...</span> 00–4F)

| 59, 7C, 92

| [[IPA Extensions]] (50–AF)

| BB–BD, '''C6, ''C7,'' C9,''' D6, '''''D8–DB,'' DC, ''DD,''''' DF, EE

| [[Spacing Modifier Letters]] (B0–FF)

! 03

| 74–75, 7A, 7E, '''84–8A, 8C, 8E–A1, A3–CE,''' D7, DA–E1

| [[Greek and Coptic|Greek]] (70–FF)

! 04

| '''00–5F, 90–91,''' 92–C4, C7–C8, CB–CC, D0–EB, EE–F5, F8–F9

| [[Cyrillic (Unicode block)|Cyrillic]] (00–FF)

! 1E

| 02–03, 0A–0B, 1E–1F, 40–41, 56–57, 60–61, 6A–6B, '''80–85,''' 9B, '''F2–F3'''

| [[Latin Extended Additional]] (00–FF)

! 1F

| 00–15, 18–1D, 20–45, 48–4D, 50–57, 59, 5B, 5D, 5F–7D, 80–B4, B6–C4, C6–D3, D6–DB, DD–EF, F2–F4, F6–FE

| [[Greek Extended]] (00–FF)

!rowspan="3"| 20

| '''13–14, ''15,'' 17, ''18–19,'' 1A–1B, ''1C–1D,'' 1E, 20–22, 26, 30, 32–33, 39–3A, 3C, 3E, 44,''' 4A

| [[General Punctuation]] (00–6F)

| '''7F''', 82

| [[Superscripts and Subscripts]] (70–9F)

| '''A3–A4, A7, ''AC,''''' AF

| [[Currency Symbols (Unicode block)|Currency Symbols]] (A0–CF)

!rowspan="3"| 21

| '''05, 13, 16, ''22, 26,'' 2E'''

| [[Letterlike Symbols]] (00–4F)

| '''''5B–5E'''''

| [[Number Forms]] (50–8F)

| '''''90–93,'' 94–95, A8'''

| [[Arrows (Unicode block)|Arrows]] (90–FF)

! 22

| 00, '''02,''' 03, '''06,''' 08–09, '''0F, 11–12, 15, 19–1A, 1E–1F,''' 27–28, '''29,''' 2A, '''2B, 48,''' 59, '''60–61, 64–65,''' 82–83, 95, 97

| [[Mathematical Operators]] (00–FF)

! 23

| '''02, 0A, 20–21,''' 29–2A

| [[Miscellaneous Technical]] (00–FF)

!rowspan="3"| 25

| '''00, 02, 0C, 10, 14, 18, 1C, 24, 2C, 34, 3C, 50–6C'''

| [[Box Drawing]] (00–7F)

| '''80, 84, 88, 8C, 90–93'''

| [[Block Elements]] (80–9F)

| '''A0–A1, AA–AC, B2, BA, BC, C4, CA–CB, CF, D8–D9, E6'''

| [[Geometric Shapes]] (A0–FF)

! 26

| '''3A–3C, 40, 42, 60, 63, 65–66, ''6A,'' 6B'''

| [[Miscellaneous Symbols]] (00–FF)

! F0

| (01–02)<!--in WGL-4, but not in MES-2-->

| [[Private Use Area (Unicode block)|Private Use Area]] (00–FF ...)

! FB

| '''01–02'''

| [[Alphabetic Presentation Forms]] (00–4F)

! FF

| FD

| [[Specials (Unicode block)|Specials]]

Rendering software which cannot process a Unicode character appropriately often displays it as an open rectangle, or the Unicode "[[replacement character]]" (U+FFFD, �), to indicate the position of the unrecognized character. Some systems have made attempts to provide more information about such characters. Apple's [[Last Resort font]] will display a substitute glyph indicating the Unicode range of the character, and the [[SIL International]]'s [[Unicode fallback font|Unicode Fallback]] font will display a box showing the hexadecimal scalar value of the character.

==={{anchor|UTF|UCS}}Mapping and encodings===

Several mechanisms have been specified for storing a series of code points as a series of bytes.

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Unicode defines two mapping methods: the ''Unicode Transformation Format'' (UTF) encodings, and the ''[[Universal Coded Character Set]]'' (UCS) encodings. An encoding maps (possibly a subset of) the range of Unicode ''code points'' to sequences of values in some fixed-size range, termed ''code units''. All UTF encodings map code points to a unique sequence of bytes.<ref>{{cite web|title=UTF-8, UTF-16, UTF-32 & BOM|url=https://unicode.org/faq/utf_bom.html|website=Unicode.org FAQ|accessdate=12 December 2016}}</ref> The numbers in the names of the encodings indicate the number of bits per code unit (for UTF encodings) or the number of bytes per code unit (for UCS encodings and UTF-1). UTF-8 and UTF-16 are the most commonly used encodings. UCS-2 is an obsolete subset of UTF-16; UCS-4 and UTF-32 are functionally equivalent.

UTF encodings include:

* [[UTF-1]], a retired predecessor of UTF-8, maximizes compatibility with [[ISO/IEC 2022|ISO 2022]], no longer part of ''The Unicode Standard''

* [[UTF-7]], a 7-bit encoding sometimes used in e-mail, often considered obsolete (not part of ''The Unicode Standard'', but only documented as an informational [[Request for Comments|RFC]], i.e., not on the Internet Standards Track)

* [[UTF-8]], uses one to four bytes for each code point, maximizes compatibility with [[ASCII]]

* [[UTF-EBCDIC]], similar to UTF-8 but designed for compatibility with [[EBCDIC]] (not part of ''The Unicode Standard'')

* [[UTF-16]], uses one or two 16-bit code units per code point, cannot encode surrogates

* [[UTF-32]], uses one 32-bit code unit per code point

UTF-8 uses one to four bytes per code point and, being compact for Latin scripts and ASCII-compatible, provides the ''de facto'' standard encoding for interchange of Unicode text. It is used by [[FreeBSD]] and most recent [[Linux distributions]] as a direct replacement for legacy encodings in general text handling.

The UCS-2 and UTF-16 encodings specify the Unicode [[Byte Order Mark]] (BOM) for use at the beginnings of text files, which may be used for byte ordering detection (or [[endianness|byte endianness]] detection). The BOM, code point U+FEFF has the important property of unambiguity on byte reorder, regardless of the Unicode encoding used; U+FFFE (the result of byte-swapping U+FEFF) does not equate to a legal character, and U+FEFF in other places, other than the beginning of text, conveys the zero-width non-break space (a character with no appearance and no effect other than preventing the formation of [[ligature (typography)|ligatures]]).

The same character converted to UTF-8 becomes the byte sequence <code>EF BB BF</code>. The Unicode Standard allows that the BOM "can serve as signature for UTF-8 encoded text where the character set is unmarked".<ref>{{Cite book | title=The Unicode Standard, Version 6.2 | publisher=The Unicode Consortium | year=2013 | isbn=978-1-936213-08-5 | page=561 }}</ref> Some software developers have adopted it for other encodings, including UTF-8, in an attempt to distinguish UTF-8 from local 8-bit [[code page]]s. However {{IETF RFC|3629}}, the UTF-8 standard, recommends that byte order marks be forbidden in protocols using UTF-8, but discusses the cases where this may not be possible. In addition, the large restriction on possible patterns in UTF-8 (for instance there cannot be any lone bytes with the high bit set) means that it should be possible to distinguish UTF-8 from other character encodings without relying on the BOM.

In UTF-32 and UCS-4, one [[32-bit]] code unit serves as a fairly direct representation of any character's code point (although the endianness, which varies across different platforms, affects how the code unit manifests as a byte sequence). In the other encodings, each code point may be represented by a variable number of code units. UTF-32 is widely used as an internal representation of text in programs (as opposed to stored or transmitted text), since every Unix operating system that uses the [[GNU Compiler Collection|gcc]] compilers to generate software uses it as the standard "[[wide character]]" encoding. Some programming languages, such as [[Seed7]], use UTF-32 as internal representation for strings and characters. Recent versions of the [[Python (programming language)|Python]] programming language (beginning with 2.2) may also be configured to use UTF-32 as the representation for Unicode strings, effectively disseminating such encoding in [[high-level programming language|high-level]] coded software.

[[Punycode]], another encoding form, enables the encoding of Unicode strings into the limited character set supported by the [[ASCII]]-based [[Domain Name System]] (DNS). The encoding is used as part of [[IDNA]], which is a system enabling the use of [[Internationalized Domain Names]] in all scripts that are supported by Unicode. Earlier and now historical proposals include [[UTF-5]] and [[UTF-6]].

[[GB 18030|GB18030]] is another encoding form for Unicode, from the [[Standardization Administration of China]]. It is the official [[character set]] of the [[People's Republic of China]] (PRC). [[Binary Ordered Compression for Unicode|BOCU-1]] and [[Standard Compression Scheme for Unicode|SCSU]] are Unicode compression schemes. The [[April Fools' Day RFC]] of 2005 specified two [[parody]] UTF encodings, [[UTF-9]] and [[UTF-18]].

==Adoption==

===Operating systems===