In Depth
See Also

Unicode

Unicode is an industry standard Industry Standard

Industry Standard is a 1982 album by The Dregs [i]. ... 

 designed to allow text and symbols from all of the writing systems Writing system

A writing system is a type of symbol [i]ic system used to represent elements or statements expressible i ... 

 of the world to be consistently represented and manipulated by computer Computer

A computer is a machine [i] for manipulating data [i] according to a list of instructions [i] ... 

s. Developed in tandem with the Universal Character Set standard and published in book form as The Unicode Standard, Unicode consists of a character repertoire, an encoding methodology and set of standard character encodings, a set of code charts for visual reference, an enumeration of character properties such as upper and lower case, a set of reference data computer file Computer file

A computer file is a piece of arbitrary information, or resources for storing information, that is avail... 

s, and rules for normalization, decomposition, collation Collation

In textual criticism [i] and bibliography [i], collation [i] is the reading of two texts side-by-side i ... 

 and rendering.

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Encyclopedia

Unicode is an industry standard Industry Standard

Industry Standard is a 1982 album by The Dregs [i]. ... 

 designed to allow text and symbols from all of the writing systems Writing system

A writing system is a type of symbol [i]ic system used to represent elements or statements expressible i ... 

 of the world to be consistently represented and manipulated by computer Computer

A computer is a machine [i] for manipulating data [i] according to a list of instructions [i] ... 

s. Developed in tandem with the Universal Character Set standard and published in book form as The Unicode Standard, Unicode consists of a character repertoire, an encoding methodology and set of standard character encodings, a set of code charts for visual reference, an enumeration of character properties such as upper and lower case, a set of reference data computer file Computer file

A computer file is a piece of arbitrary information, or resources for storing information, that is avail... 

s, and rules for normalization, decomposition, collation Collation

In textual criticism [i] and bibliography [i], collation [i] is the reading of two texts side-by-side i ... 

 and rendering.

The Unicode Consortium Unicode Consortium

The Unicode Consortium, the non-profit organization that coordinates Unicode [i]'s development, has the... 

, the non-profit organization that coordinates Unicode's development, has the ambitious goal of eventually replacing existing character encoding schemes with Unicode and its standard Unicode Transformation Format schemes, as many of the existing schemes are limited in size and scope, and are incompatible with multilingual Multilingualism

The term multilingualism can refer to phenomena regarding an individual speaker who uses two or more lan... 

 environments. Unicode's success at unifying character sets has led to its widespread and predominant use in the internationalization and localization of computer software Computer software

Software fundamentally is the unique image or representation of physical or material alignment that ... 

. The standard has been implemented in many recent technologies, including XML, the Java programming language Java (programming language)

Java is an object-oriented [i] programming language [i] developed by James Gosling [i] ... 

, and modern operating system Operating system

An operating system is a software program [i] that manages the hardware [i] and software [i] ... 

s.

Origin and development


Unicode has the explicit aim of transcending the limitations of traditional character encodings, such as those defined by the ISO 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 , but not multilingual computer processing .

Unicode, in intent, encodes the underlying characters — graphemes and grapheme-like units — rather than the variant glyph Glyph

In typography [i], a glyph is the shape given in a particular typeface [i] to a specific grapheme [i] or ... 

s for such characters. In the case of Chinese character Chinese character

A Chinese character is a logogram [i] used in writing Chinese [i], Japanese [i] ... 

s, this sometimes leads to controversies over distinguishing the underlying character from its variant glyphs .

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 to other software, such as a web browser Web browser

A web browser is a software application [i] that enables a user to display and int... 

 or word processor Word processor

A word processor is a computer [i] application [i] used for the production of any ... 

. This simple aim becomes complicated, however, by 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 8859-1, to make it trivial to convert existing western text. A lot of 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 without losing any information. For example, the "fullwidth forms" section of code points encompasses a full Latin alphabet that is separate from the main Latin alphabet section. In Chinese, Japanese, and Korean fonts, these characters are rendered at the same width as CJK ideographs rather than at half the width. For other examples, see Duplicate characters in Unicode.

Also, while Unicode allows for combining characters, it also contains 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 ι can be represented in Unicode as followed by U+0301 but it can also be represented as the precomposed character U+00E9 .

The Unicode standard also includes a number of related items, such as character properties, text normalisation forms, and bidirectional display order .

Scripts covered


Unicode covers almost all scripts in current use today, including:

  • Arabic Arabic alphabet

    The Arabic alphabet is the script [i] used for writing Arabic [i] and var... 

  • Armenian Armenian alphabet

    This article was written by a non-native speaker.... 

  • Bengali
  • Braille Braille

    The braille system, devised in 1821 [i] by Louis Braille [i], is a method that is widely used by blind [i] ... 

     embossing patterns
  • Canadian Aboriginal Syllabics Canadian Aboriginal Syllabics

    Canadian Aboriginal syllabic writing is a family of abugida [i]s used to write a number of Aboriginal [i] ... 

  • Cherokee Cherokee language

    Cherokee is an Iroquoian language [i] spoken by the Cherokee [i] people.... 

  • Coptic Coptic alphabet

    The Coptic alphabet is an alphabet [i] used for writing the Coptic language [i]. ... 

  • Cyrillic Cyrillic alphabet

    The Cyrillic alphabet is an alphabet [i] used for several East and South Slavic languages [i]; and many other languages [i] ... 

  • Devanagari Devanagari

    Devanagari is an abugida [i] writing system [i] used to write [i], either along with other scri... 

  • Ethiopic Ge'ez language

    Ge'ez is an ancient South Semitic [i] language [i] that had developed in the current region of Eritrea [i] ... 

  • Georgian Georgian alphabet

    The Georgian alphabet is the script currently used to write the Georgian language [i] and other Kartvelian [i] ... 

  • Greek Greek alphabet

    The Greek alphabet is an alphabet [i] that has been used to write the Greek language [i] since about t ... 

  • Gujarati Gujarati script

    [i] writing systems is strictly speaking an [[abugida]... 

  • Gurmukhi
  • Han Chinese character

    A Chinese character is a logogram [i] used in writing Chinese [i], Japanese [i] ... 

  • Hangul Hangul

    Hangul , or Chosongul is the native alphabet [i] of the Korean language [i], as opposed to the no ... 

  • Hebrew
  • Hiragana Hiragana

    are a Japanese [i] syllabary [i], one of the four Japanese writing system [i]s, along ... 

     and Katakana Katakana

    Katakana is a Japanese [i] syllabary [i], one of the four Japanese writing system [i] ... 

  • International Phonetic Alphabet International Phonetic Alphabet

    The International Phonetic Alphabet is a system of phonetic notation [i] devised ... 

  • Khmer Khmer script

    The Khmer script is used to write the Khmer language [i] which is the official language of Cambodia [i]. ... 

  • Kannada
  • Lao
  • Latin Latin alphabet

    The Latin alphabet, also called the Roman alphabet, is the most widely used alphabet [i]ic writing system [i] ... 

  • Malayalam Malayalam script

    The Malayalam script is an abugida [i] of the Brahmic family [i], used to write the Malayalam language [i] ... 

  • Mongolian Mongolian alphabet

    Mongolian alphabet may refer to any of three scripts used over the centuries to write the Mongolian language [i] ... 

  • Myanmar Burmese alphabet

    The Burmese abugida is a script in the Brahmic family [i] used in Myanmar [i] for writing Burmese [i]... 

  • Oriya Oriya script

    The Oriya script is used to write the Oriya language [i], and several other Indian languages like Sanskrit [i] ... 

  • Syriac Syriac alphabet

    The Syriac alphabet is a writing system [i] used to write the Syriac language [i] from around the 2nd century BC [i] ... 

  • Tamil Tamil script

    The Tamil script is an Indic script [i] that is used to write the Tamil language [i]. ... 

  • Telugu
  • Thai Thai alphabet

    The Thai alphabet [i] is used to write the Thai language [i] and other minority language [i]s in Thailand [i] ... 

  • Tibetan Tibetan script

    The Tibetan script is an abugida [i] of Indic [i] origin used to write the Tibetan language [i] ... 

  • Tifinagh Tifinagh

    Tifinagh , or ??????? is an alphabetic script used by some Berber [i]s to write their language. ... 

  • Yi
  • Zhuyin Zhuyin

    Zhuyin Fuhao , or "Symbols for Annotating Sounds", often abbreviated as Zhuyin, or known as Bop... 




Unicode has added further scripts and will cover even more, including historic scripts less commonly used as well as extinct ones for academic purposes:

  • Cuneiform Cuneiform script

    The cuneiform script is one of the earliest known forms of written expression [i]. ... 

  • Deseret Deseret alphabet

    The Deseret alphabet is a phonetic [i] alphabet [i] developed in the mid-19th century [i] by t ... 

  • Linear B Linear B

    Linear B is a script that was used for writing Mycenaean [i], an early form of Greek [i] ... 

  • Ogham Ogham

    Ogham was an alphabet [i] used primarily to represent Gaelic [i] languages. ... 

  • Old Italic Old Italic alphabet

    Old Italic refers to several now extinct alphabet [i] systems used on the Italian Peninsula [i] in ancie ... 

  • Phoenician Phoenician alphabet

    The Phoenician alphabet is a continuation of the Proto-Canaanite alphabet [i], by convention taken to be... 

  • Runic Runic alphabet

    The Runic alphabets are a set of related alphabet [i]s using letters, formerly used to write Germanic languages [i] ... 

  • Shavian Shavian alphabet

    Posthumously funded by and named after Irish [i] playwright George Bernard Shaw [i], the Shavian al ... 

  • Ugaritic Ugaritic alphabet

    The Ugaritic alphabet is a cuneiform [i] abjad [i], used from around 1300 BC for the Ugaritic language, ... 




Further additions of characters to the already-encoded scripts, as well as symbols, in particular for mathematics Mathematics

Mathematics is the discipline that deals with concepts such as quantity [i], structure [i], space [i] a ... 

 and music Music

Music is an art, entertainment [i], or other human activity that involves organized and audible sounds a ... 

 , also occur. The lists scripts not yet in Unicode with tentative assignments to code blocks. Invented scripts, most of which do not qualify for inclusion in Unicode due to lack of real-world usage, are listed in the ConScript Unicode Registry, along with unofficial but widely-used Private Use Area Mapping of Unicode characters

Unicode [i] reserves 1,114,112 code points.
... 

 code assignments. Similarly, many medieval letter variants and ligatures not in Unicode are encoded in the Medieval Unicode Font Initiative.

Mapping and encodings


Standard


The Unicode Consortium Unicode Consortium

The Unicode Consortium, the non-profit organization that coordinates Unicode [i]'s development, has the... 

, based in California California

California is a state [i] spanning the southern half of the west coast [i] ... 

, develops the Unicode standard. Any company or individual willing to pay the membership dues may join this organization. Members include virtually all of the main computer software and hardware companies with any interest in text-processing standards, such as Apple Computer Apple Computer

Apple Computer, Inc. is an American [i] computer [i] technology [i] corporation [i] with ... 

, Microsoft Microsoft

company_name = Microsoft Corporation
... 

, IBM IBM

company_name = International Business Machines Corporation |
... 

, Xerox Xerox

Xerox Corporation is an American [i] document management [i] company, which manufactures... 

, HP Hewlett-Packard

The Hewlett-Packard Company , commonly known as HP, is one of the world's largest information technology [i] ... 

, Adobe Systems Adobe Systems

Adobe Systems is an American [i] computer [i] software [i] company hea... 

 and many others.

The Consortium first published The Unicode Standard in 1991, and continues to develop standards based on that original work. Unicode developed in conjunction with the International Organization for Standardization International Organization for Standardization

The International Organization for Standardization is an international standard-setting body composed o... 

, and it shares its 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, collation, and rendering. The Unicode Standard enumerates a multitude of character properties, including those needed for supporting bidirectional text. The two standards do use slightly different terminology.


Unicode revision history

Storage, transfer, and processing


So far, Unicode has appeared simply as a means to assign a unique number to each character used in the written languages of the world. The storage of these numbers in text processing comprises another topic; problems result from the fact that much software Computer software

Software fundamentally is the unique image or representation of physical or material alignment that ... 

 written in the Western world Western world

The term Western World or "the West" can have multiple meanings depending on its context.... 

 deals with 8-bit or lower character encodings only, with Unicode support added only slowly in recent years. Similarly, in representing the scripts of Asia Asia

Asia is the largest and most populous continent [i] or region, depending on the definition.... 

, the ASCII ASCII

ASCII , generally pronounced [i] , is a character encoding [i] based on the English alphabet [i] ... 

 based double-byte character encodings cannot even in principle encode more than 32,768 characters, and in practice the architectures chosen impose lower limits. Such limits do not suffice for the needs of scholars of the Chinese language Chinese language

Chinese is a language [i] that forms part of the Sino-Tibetan family [i] of lan ... 

 alone.

The internal logic of much 8-bit legacy software typically permits only 8 bits for each character, making it impossible to use more than 256 code points without special processing. Sixteen-bit software can support only some tens of thousands of characters. Unicode, on the other hand, has already defined more than 100,000 encoded characters. Systems designers have therefore suggested several mechanisms for implementing Unicode; which one implementers choose depends on available storage space, source code Source code

Source code is any series of statements written in some human-readable [i] computer programming language [i] ... 

 compatibility, and interoperability with other systems.

Unicode defines two mapping methods:

  • the UTF encodings
  • the UCS encodings


The encodings include:

  • UTF-7 — a relatively unpopular 7-bit encoding, suited for transmission and storage only; it is often considered obsolete
  • UTF-8 UTF-8

    UTF-8 is a variable-length [i] character encoding [i] for Unicode [i] created b ... 

     — an 8-bit, variable-width encoding, compatible with ASCII ASCII

    ASCII , generally pronounced [i] , is a character encoding [i] based on the English alphabet [i] ... 

    .
  • UCS-2 — a 16-bit, fixed-width encoding that only supports the BMP Mapping of Unicode characters

    Unicode [i] reserves 1,114,112 code points.

... 


  • UTF-16 — a 16-bit, variable-width encoding
  • UCS-4 and UTF-32 — functionally identical 32-bit fixed-width encodings
  • UTF-EBCDIC — an encoding intended for EBCDIC based mainframe systems


The numbers in the names of the encodings indicate the number of bits in one code value or the number of bytes per code value encodings.

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

UTF-16, meanwhile, which is usually 16 bits per code point — the same as UCS-2 — but sometimes 32, is used by many APIs. Most of this is for historical reasons . UTF-16 is the standard format for the Windows API and for the Java and .NET bytecode environments.

UCS-2 is an obsolete, 16-bit fixed-width encoding covering the Basic Multilingual Plane Mapping of Unicode characters

Unicode [i] reserves 1,114,112 code points.
... 

 only. For characters in the Basic Multilingual Plane UCS-2 and UTF-16 are identical. Therefore they can be considered as different implementation levels of the same encoding. The UCS-2 and UTF-16 encodings specify the Unicode Byte Order Mark  for use at the beginnings of text files. Some software developers have adopted it for other encodings, including UTF-8, which does not need an indication of byte order. In this case it attempts to mark the file as containing Unicode text. The BOM, code point U+FEFF has the important property of unambiguity, regardless of the Unicode encoding used. The units FE and FF never appear in UTF-8 UTF-8

UTF-8 is a variable-length [i] character encoding [i] for Unicode [i] created b ... 

; U+FFFE does not equate to a legal character, and U+FEFF conveys the zero-width no-break space . The same character converted to UTF-8 becomes the byte sequence EF BB BF.

In UTF-32 and UCS-4, one 32-bit code value serves as a fairly direct representation of any character's code point . In the other cases, each code point may be represented by a variable number of code values. UCS-4 and UTF-32 are not commonly used, since no more than 21 of the 32 bits allocated per code point would ever be used, but it is becoming increasingly common for programming language implementations to use UCS-4 for their internal storage of encoded text.

Punycode, another encoding form, enables the encoding of Unicode strings into the limited character set supported by the ASCII ASCII

ASCII , generally pronounced [i] , is a character encoding [i] based on the English alphabet [i] ... 

-based Domain Name System Domain name system

The domain name system stores and associates many types of information with domain name [i]s, but most ... 

. The encoding is used as part of IDNA Internationalized domain name

An internationalized domain name is an Internet [i] domain name [i] that contains non-ASCII [i] characte ... 

, which is a system enabling the use of Internationalized Domain Names Internationalized domain name

An internationalized domain name is an Internet [i] domain name [i] that contains non-ASCII [i] characte ... 

 in all languages that are supported by Unicode.

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 People's Republic of China

The People's Republic of China , is a country [i] in East Asia [i]. ... 

 .

Ready-made versus composite characters


Unicode includes a mechanism for modifying character shape and so greatly extending the supported glyph repertoire. This covers the use of combining diacritical marks. They get inserted after the main character . However, for reasons of compatibility, Unicode also includes a large quantity of pre-composed characters. So in many cases, users have many ways of encoding the same character. To deal with this, Unicode provides the mechanism of canonical equivalence.

An example of this arises with Hangul Hangul

Hangul , or Chosongul is the native alphabet [i] of the Korean language [i], as opposed to the no ... 

, the Korean alphabet. Unicode provides the mechanism for composing Hangul syllables with their individual subcomponents, known as Hangul Jamo Hangul

Hangul , or Chosongul is the native alphabet [i] of the Korean language [i], as opposed to the no ... 

. However, it also provides all 11,172 combinations of precomposed Hangul syllables.

The CJK ideographs currently have codes only for their precomposed form. Still, most of those ideographs evidently comprise simpler elements , so in principle Unicode could decompose them just as happens with Hangul Hangul

Hangul , or Chosongul is the native alphabet [i] of the Korean language [i], as opposed to the no ... 

. This would greatly reduce the number of required code points, while allowing the display of virtually every conceivable ideograph . A similar idea covers some input method Input method editor

An input method editor is a program or operating system [i] component that allows computer users to ente ... 

s, such as Cangjie Cangjie method

The Cangjie method, often erroneously spelt Changjei method, is a system by which Chinese character [i] ... 

 and Wubi. However, attempts to do this for character encoding have stumbled over the fact that ideographs do not actually decompose as simply or as regularly as it seems they should.

A set of radicals was provided in Unicode 3.0 , but the Unicode standard warns against using ideographic description sequences as an alternate representation for previously encoded characters:

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, ideograph descriptions are more akin to the English phrase, “an ‘e’ with an acute accent on it,” than to the character sequence <U+006E, U+0301>.

Ligatures

Many languages, including Arabic Arabic language

The Arabic language , or simply Arabic , is the largest member of the Semitic [i] branch of the Afro-Asiatic [i] ... 

 and Hindi Devanagari

Devanagari is an abugida [i] writing system [i] used to write [i], either along with other scri... 

, have special orthographic rules which require that certain combinations of letterforms be combined into special ligature forms. The rules governing ligature formation can be quite complex, requiring special script-shaping technologies such as OpenType , Graphite Graphite

Graphite is one of the allotropes of [i] carbon [i]. ... 

 , or AAT Apple Advanced Typography

Apple Advanced Typography is Apple Computer [i]'s computer software for advanced font [i] rendering, sup ... 

 . Instructions are also embedded in fonts to tell the operating system Operating system

An operating system is a software program [i] that manages the hardware [i] and software [i] ... 

 how to properly output different character sequences. In simpler cases, such as the placement of combining marks or diacritics, fixed-width fonts sometimes employ a method known as "sidebearing" in which the special marks preceed the main letterform in the datastream and the font rendering software knows to combine the marks into a final form. This method works only for some diacritics, and may fail to properly handle stacked marks.

As of 2004 2004

2004 was a leap year starting on Thursday [i] of the Gregorian calendar [i].
... 

, most software still cannot reliably handle many features not supported by older font formats, so combining characters generally will not work correctly. For example, and should be rendered identically, both appearing as an e E

The letter E is the fifth letter in the Latin alphabet [i]. ... 

 with a macron and acute accent, but in practice, their appearance can vary greatly across software applications. Similarly, underdots, as needed in the romanization of Indic, will often be placed incorrectly. As a workaround, Unicode characters that map to precomposed glyphs can be used for many such characters. The need for such alternatives inherits from the limitations of fonts and rendering technology, not weaknesses of Unicode itself.

Unicode in use


Operating systems


Unicode has become the dominant scheme for internal processing and sometimes storage of text. Early adopters tended to use UCS-2 and later moved to UTF-16 . The best known such system is Windows NT Windows NT

Windows NT is a family of operating system [i]s produced by Microsoft [i], the first version of which wa... 

 . The Java and .NET .NET Framework

The Microsoft .NET Framework is a software component [i] which can be added to the ... 

 bytecode environments, Mac OS X, and also Unix desktops such as KDE and GNOME, also use it.

UTF-8 UTF-8

UTF-8 is a variable-length [i] character encoding [i] for Unicode [i] created b ... 

  has become the main encoding on most Unix-like Unix-like

A "Unix-like" operating system [i] is one that behaves in a manner similar to a Unix [i] system, while n... 

 operating systems because it is a relatively easy replacement for traditional extended ASCII character sets.

E-mail



MIME defines two different mechanisms for encoding non-ASCII characters in e-mail E-mail

Electronic mail is a store and forward [i] method of composing, sending, storing, and receiving message ... 

, depending on whether the characters are in e-mail headers such as the "Subject:" or in the text body of the message. In both cases, the original character set is identified as well as a transfer encoding. For e-mail transmission of Unicode the UTF-8 character set and the Base64 transfer encoding are recommended. The details of the two different mechanisms are specified in the MIME standards and are generally hidden from users of e-mail software.

The adoption of Unicode in e-mail E-mail

Electronic mail is a store and forward [i] method of composing, sending, storing, and receiving message ... 

 has been very slow. Most East-Asian text is still encoded in a local encoding such as Shift-JIS, and many commonly used e-mail programs still cannot handle Unicode data correctly, if they have any support at all. This situation is not expected to change in the foreseeable future.

Web


Web browsers have been supporting severals UTFs, especially UTF-8, for many years now. Display problems result primarily from font Typeface

In typography [i], a typeface consists of a coordinated set [i] of glyph [i]s designed with stylistic un ... 

 related issues. In particular Internet Explorer Internet Explorer

Internet Explorer, abbreviated IE or WIE , is a proprietary [i] graphical [i]... 

 does not render many code points unless it is explicitly told to use a font that contains them.

All W3C World Wide Web Consortium

The World Wide Web Consortium is an international consortium [i] where , a full-time staff and the publ ... 

 recommendations are using Unicode as their document character set, the encoding being variable, ever since HTML 4.0. It replaces the 8-bit ASCII superset ISO-8859-1, which had been the standard character set and encoding before.

Although syntax rules may affect the order in which characters are allowed to appear, both HTML 4 HTML

In computing, HyperText Markup Language is a predominant markup language [i] for the creation of web page [i] ... 

 and XML  documents, by definition, comprise characters from most of the Unicode code points, with the exception of:
  • most of the C0 and C1 control codes
  • the permanently-unassigned code points D800–DFFF
  • any code point ending in FFFE or FFFF
  • any code point above 10FFFF.

These characters manifest either directly as bytes according to document's encoding, if the encoding supports them, or users may write them as numeric character references based on the character's Unicode code point.

For example, the references &#916;, &#1049;, &#1511;, &#1605;, &#3671;, &#12354;, &#21494;, &#33865;, and &#45307; display on browsers as ?, ?, ?,? ?, ?, ?, ?, ? and ?. If the proper fonts exist, these symbols look like the Greek Greek alphabet

The Greek alphabet is an alphabet [i] that has been used to write the Greek language [i] since about t ... 

 capital letter "Delta", Cyrillic Cyrillic alphabet

The Cyrillic alphabet is an alphabet [i] used for several East and South Slavic languages [i]; and many other languages [i] ... 

 capital letter "Short I Short I

Short I is a letter in the Cyrillic alphabet [i]. ... 

", Hebrew letter "Qof", Arabic Arabic alphabet

The Arabic alphabet is the script [i] used for writing Arabic [i] and var... 

 letter "Meem", Thai numeral 7, Japanese Japanese language

Japanese is a language spoken by over 127 million people, mainly in Japan [i], but also by Japanese emi ... 

 Hiragana Hiragana

are a Japanese [i] syllabary [i], one of the four Japanese writing system [i]s, along ... 

 "A", simplified Chinese "Leaf Leaf

In botany [i], a leaf is an above-ground plant [i] organ [i] specialized for photosynthesis [i]. ... 

", traditional Chinese "Leaf", and Korean Korean language

The Korean language is the official language of both North [i] and South Korea [i]. ... 

 Hangul Hangul

Hangul , or Chosongul is the native alphabet [i] of the Korean language [i], as opposed to the no ... 

 syllable "Nyaelh", respectively.

In HTTP requests, URLs must be percent-encoded, usually using the UTF-8 UTF-8

UTF-8 is a variable-length [i] character encoding [i] for Unicode [i] created b ... 

 encoding to represent Unicode.

Fonts


Free and retail fonts Unicode typefaces

[i], [[symbols]... 

 based on Unicode occur commonly, since first TrueType and now OpenType support Unicode. These font formats map Unicode code points to glyphs.

Thousands of fonts exist on the market, but fewer than a dozen fonts — sometimes described as "pan-Unicode" fonts — attempt to support the majority of Unicode's character repertoire. Instead, Unicode-based fonts typically focus on supporting only basic ASCII and particular scripts or sets of characters or symbols. Several reasons justify this approach: applications and documents rarely need to render characters from more than one or two writing systems; fonts tend to demand resources in computing environments; and operating systems and applications show increasing intelligence in regard to obtaining glyph information from separate font files as needed. Furthermore, designing a consistent set of rendering instructions for tens of thousands of glyphs constitutes a monumental task; such a venture passes the point of diminishing returns for most typefaces.

Several subsets of Unicode are standardized: Microsoft Windows since Windows NT 4.0 supports WGL-4 with 652 characters, which is considered to support all contemporary European languages using the Latin, Greek or Cyrillic script. Other standardized subsets of Unicode include MES-1 and MES-2 .
style="font-family:sans-serif; font-style: normal;"| WGL-4, MES-1 and MES-2
Row Cells Range
00 20–7E Basic Latin
A0–FF Latin-1 Supplement
01 00–13, 14–15, 16–2B, 2C–2D, 2E–4D, 4E–4F, 50–7E, 7F Latin Extended-A
8F, 92, B7, DE-EF, FA–FF Latin Extended-B
02 18–1B, 1E–1F Latin Extended-B
59, 7C, 92 IPA Extensions
BB–BD, C6, C7, C9, D6, D8–DB, DC, DD, DF, EE Spacing Modifier Letters
03 74–75, 7A, 7E, 84–8A, 8C, 8E–A1, A3–CE, D7, DA–E1 Greek
04 00, 01–0C, 0D, 0E–4F, 50, 51–5C, 5D, 5E–5F, 90–91, 92–C4, C7–C8, CB–CC, D0–EB, EE–F5, F8–F9 Cyrillic
1E 02–03, 0A–0B, 1E–1F, 40–41, 56–57, 60–61, 6A–6B, 80–85, 9B, F2–F3 Latin Extended Additional
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
20 13–14, 15, 17, 18–19, 1A–1B, 1C–1D, 1E, 20–22, 26, 30, 32–33, 39–3A, 3C, 3E General Punctuation
44, 4A, 7F, 82 Superscripts and Subscripts
A3–A4, A7, AC, AF Currency Symbols
21 05, 13, 16, 22, 26, 2E Letterlike Symbols
5B–5E Number Forms
90–93, 94–95, A8 Arrows
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
23 02, 0A, 20–21, 29–2A Miscellaneous Technical
25 00, 02, 0C, 10, 14, 18, 1C, 24, 2C, 34, 3C, 50–6C Box Drawing
80, 84, 88, 8C, 90–93 Block Elements
A0–A1, AA–AC, B2, BA, BC, C4, CA–CB, CF, D8–D9, E6 Geometric Shapes
26 3A–3C, 40, 42, 60, 63, 65–66, 6A, 6B Miscellaneous Symbols
F0 Private Use Area
FB 01–02 Alphabetic Presentation Forms
FF FD Specials


Rendering software which cannot process a Unicode character appropriately most often display it as only an open rectangle, or the Unicode "Replacement Character" , to indicate the position of the unrecognized character. Some systems have made attempts to provide more information about such characters. The Apple LastResort Fallback font

A fallback font [i] is a reserve typeface containing symbols for all Unicode [i] characters [i] ... 

font will display a substitute glyph indicating the Unicode range of the character and the SIL Unicode fallback font Fallback font

A fallback font [i] is a reserve typeface containing symbols for all Unicode [i] characters [i] ... 

 will display a box showing the hexadecimal scalar value of the character.

Multilingual text-rendering engines

  • Uniscribe — Windows Microsoft Windows

    Microsoft Windows is a family of operating system [i]s by Microsoft [i].... 

  • Apple Type Services for Unicode Imaging — new engine for Macintosh Macintosh

    The Macintosh, or Mac, is a line of personal computer [i]s designed, developed, manufactured, and ... 

  • WorldScript — old engine for Macintosh Macintosh

    The Macintosh, or Mac, is a line of personal computer [i]s designed, developed, manufactured, and ... 

  • Pango — Open Source Open source

    Open source describes practices in production and development that promote access to the end product's s... 

    , used by GTK+ GTK+

    The GIMP Toolkitabbreviated, and almost exclusively known, as GTK+is one of the two most popular widget toolkit [i] ... 

  • ICU Layout Engine — Open Source
  • Graphite Graphite

    Graphite is one of the allotropes of [i] carbon [i]. ... 

      —
  • Scribe — Open Source renderer from Trolltech Trolltech

    Trolltech is a computer software company from Oslo [i], Norway [i]. ... 



Input methods


Because keyboard layouts cannot have simple key combinations for all characters, several operating systems provide alternative input methods that allow access to the entire repertoire.

In Microsoft Windows Microsoft Windows

Microsoft Windows is a family of operating system [i]s by Microsoft [i].... 

 , the "Character Map" program provides rich-text editing controls for all Table I characters up to U+FFFF, by selection from a drop-down table, assuming that a Unicode font Typeface

In typography [i], a typeface consists of a coordinated set [i] of glyph [i]s designed with stylistic un ... 

 is selected. Programs such as Microsoft Word Microsoft Word

Microsoft Word, or Microsoft Office Word, is Microsoft [i]'s flagship word processing [i] ... 

 have a similar control embedded . Rather more painfully and where the code point of the desired character is known, it is possible to create Unicode characters by pressing Alt + #, where # represents 0 followed by the decimal code point; for example, Alt + 0241 will produce the Unicode character ρ. This also works in many other Windows applications, but not in applications that use the standard Windows edit control, and do not make any special provisions to allow this type of input. See Alt codes. To add Unicode characters to chart titles in Microsoft Excel Microsoft Excel

Microsoft Excel is a spreadsheet [i] program written and distributed by Microsoft [i] for computers us ... 

 first type the title text into a worksheet cell, where the control can be used. The resulting text can be cut and pasted into chart titles.

Apple Macintosh Macintosh

The Macintosh, or Mac, is a line of personal computer [i]s designed, developed, manufactured, and ... 

 users have a similar feature with an input method called 'Unicode Hex Input', in Mac OS X Mac OS X

Mac OS X is a line of proprietary [i], graphical operating system [i]s developed, ... 

 and in Mac OS Mac OS

Mac OS, which stands for Macintosh Operating System, is a series of graphical user interface [i]... 

 8.5 and later: hold down the Option key, and type the four-hex-digit Unicode code point. Inputting code points above U+FFFF is done by entering surrogate pairs; the software will convert each pair into a single character automatically. Mac OS X also has a 'Character Palette', which allows users to visually select any Unicode character from a table organized numerically, by Unicode block, or by a selected font's available characters. The 'Unicode Hex Input' method must be activated in the International System Preferences in Mac OS X Mac OS X

Mac OS X is a line of proprietary [i], graphical operating system [i]s developed, ... 

 or the 'Keyboard' Control Panel in Mac OS Mac OS

Mac OS, which stands for Macintosh Operating System, is a series of graphical user interface [i]... 

 8.5 and later. Once activated, 'Unicode Hex Input' must also be selected in the Keyboard menu before a Unicode code point can be entered.

GNOME Gnome

A gnome is a legendary creature [i] characterized by its very small stature and subterranean lifestyle.... 

 provides a 'Character Map' utility which displays characters ordered by Unicode block or by writing system, and allows searching by character name or extended description. Where the character's code point is known, it can be entered in accordance with ISO 14755: hold down Ctrl and Shift and enter the hexadecimal Unicode value, preceded by the letter U if using GNOME 2.15 or later. Because Gnome uses UTF-8 UTF-8

UTF-8 is a variable-length [i] character encoding [i] for Unicode [i] created b ... 

 internally, this method works in all applications and surrogate pairs are not needed.

At the X Input Method X Window System

In computing [i], the X Window System provides windowing [i] for bitmap [i] ... 

 or GTK+ Input Module level, the input method editor SCIM SCIM

The Smart Common Input Method platform, is an input method [i] platform supporting more tha ... 

 provides a “raw code” input method to allow the user to enter the 4-digit hexadecimal Unicode value.

All X Window X Window System

In computing [i], the X Window System provides windowing [i] for bitmap [i] ... 

 applications support using the Compose Key Compose key

On some computer [i] systems, a compose key is a key which is designated to signal the software [i] to i ... 

. For keyboards which do not have a designated Compose key, another key could be redefined as a Compose key.

The Linux Linux

Linux is a Unix-like [i] computer operating system [i]. ... 

 console allows Unicode characters to be entered by holding down Alt and typing the decimal code on the numeric keypad Keypad

A keypad is a set of buttons arranged in a block which usually bear digits and other symbols but not a c... 

. The AltGr key allows the hexadecimal code to be entered instead, using NumLock-Enter as A-F . ISO 14755 compliant input is also available in the unicode keymap.

The Opera web browser Opera

Opera is a dramatic [i] art [i] form, originating in Italy [i], in which the emotional content or... 

 in version 7.5 and over allows users to enter any Unicode character directly into a text field by typing its hexadecimal code, selecting it, and pressing Alt + x.

To input a Unicode character in a text box in Mozilla Firefox Mozilla Firefox

Mozilla Firefox is a free [i], open source [i], cross-platform [i], graphical [i] ... 

 on Linux, type the hexadecimal character code while holding down the control and shift keys.

In the Vim text editor, Unicode characters can be entered by pressing CTRL-V and then entering a key combination. For more information, type ":help i_CTRL-V_digit" in Vim. Many Unicode characters can also be entered using digraphs; a table of such characters and their corresponding digraphs can be obtained using the ":digraphs" command .

WordPad and Word 2002/2003 for Windows additionally allow for entering Unicode characters by typing the hexadecimal code point, for example 014B for ?, and then pressing Alt + x to substitute the string to the left by its Unicode character. Usefully, the reverse also applies: if a user positions a cursor to the right of a non-ASCII character and presses Alt + x, then the Microsoft software will substitute the character with the hexadecimal Unicode code point.

Several visual keyboards are available that make entering Unicode characters and symbols very easy.


Issues


Some people, mostly in Japan Japan

is an island country [i] in East Asia [i]. ... 

, oppose Unicode in general, claiming technical limitations and political problems in its operation. People working on the Unicode standard regard such claims simply as misunderstandings of the Unicode standard and of the process by which it has evolved. The most common mistake, according to this view, involves confusion between abstract characters and their highly-variable visual forms . On the other hand, whereas Chinese Chinese language

Chinese is a language [i] that forms part of the Sino-Tibetan family [i] of lan ... 

 can readily read most types of glyphs used by Japanese or Korea Korea

Korea
One of the world's oldest civilization [i]s, Korea began with the founding of Gojoseon [i] in 2333 ... 

ns, Japanese often can recognize only a particular variant.

Some have decried Unicode as a plot against Asian cultures perpetrated by Westerners with no understanding of the characters as used in Chinese, Korean, and Japanese, despite the presence of a majority of experts from all three regions in the Ideographic Rapporteur Group . The IRG advises the consortium and ISO on additions to the repertoire and on Han unification, the identification of forms in the three languages which one can treat as stylistic variations of the same historical character. Han unification has become one of the most controversial aspects of Unicode.

Unicode is criticized for failing to allow for older and alternate forms of kanji Kanji

Kanji are the Chinese character [i]s that are used in the modern Japanese [i] logographic writing system [i]... 

 which, critics argue, complicates the processing of ancient Japanese and uncommon Japanese names, although it follows the recommendations of Japanese language scholars and of the Japanese government. There have been several attempts to create an alternative to Unicode. Among them are TRON , and UTF-2000.

It is true that many older forms were not included in early versions of the Unicode standard, but Unicode 4.0 contains more than 90,000 Han characters, far more than any dictionary or any other standard, and work continues on adding characters from the early literature of China, Korea, and Japan. Some argue, however, that this is not satisfactory, pointing out as an example the need to create new characters, representing words in various Chinese dialects Spoken Chinese

Spoken [i] Chinese [i] comprises many regional variants. ... 

, more of which may be invented in the future.

An alternative way, pursued by people like Chu Bong-Foo, uses encoding which provides information on the radicals making up Han characters. For example, a 1991 Chinese computing system by Chu already provides 60,000 Han characters support, and takes up only 80KB memory space for the generation of glyphs from raw Cangjie Cangjie method

The Cangjie method, often erroneously spelt Changjei method, is a system by which Chinese character [i] ... 

 codes.

Their argument against Unicode is that the Unicode approach to Han characters is the same as assigning every English word with a separate code.

Thai language support has been criticized for its illogical ordering of Thai characters. This complication is due to Unicode inheriting the Thai Industrial Standard 620, which worked in the same way. This ordering problem complicates the Unicode collation process.

Indic Scripts such as Tamil Tamil script

The Tamil script is an Indic script [i] that is used to write the Tamil language [i]. ... 

 are each allocated only 128 slots of the Unicode space, matching the ISCII standard. The correct rendering of Unicode Indic text requires transforming the stored logical order characters into visual order and the forming of compound characters out of components. Especially for Tamil, local scholars are arguing in favor of an assignment of Unicode codepoint to compound characters. This will most likely not happen, as can be seen of the case of Tibetan script where even the Chinese National Standard organization failed to achieve a similar change.

Opponents of Unicode sometimes erroneously claim even now that it cannot handle more than 65,535 characters, even though this limitation was removed in Unicode 2.0.

Trivia


In 1997 Michael Everson Michael Everson

Michael Everson is a linguist [i], script encoder [i], typesetter [i], an ... 

 made a proposal to encode the characters of the fictional Klingon language Klingon language

The Klingon language or Klingonese is the constructed language [i] spoken by Klingon [i]s in the ... 

 in Plane 1 of ISO/IEC 10646-2. The Unicode Consortium Unicode Consortium

The Unicode Consortium, the non-profit organization that coordinates Unicode [i]'s development, has the... 

 rejected this proposal in 2001 as "inappropriate for encoding" — not because of any technical inadequacy, but because users of Klingon normally read, write and exchange data in Latin Latin

Latin is an ancient Indo-European language [i] originally spoken in Latium [i], ... 

 transliteration. Now that some enthusiasts are blogging in tlhIngan pIqaD Klingon language

The Klingon language or Klingonese is the constructed language [i] spoken by Klingon [i]s in the ... 

  using newly available fonts and keyboard layouts, the possibility of reapplying to ISO has been raised.

Proposals suggested the inclusion of the elvish Elf

The economic outlook of Afghanistan [i]'s Economy has improved significantly since 2002 [i] due to the i ... 

 scripts Tengwar Tengwar

Tengwar is an artificial script [i] which was invented by J. R. R. Tolkien [i]. ... 

 and Cirth Cirth

The Cirth are the letters of an artificial script [i] which was invented by J. R. R. Tolkien [i] for th ... 

 from J. R. R. Tolkien J. R. R. Tolkien

John Ronald Reuel Tolkien CBE [i] is best known as the author of The Hobbit [i] ... 

's fictional Middle-earth Middle-earth

Middle-earth is an historical term.... 

 setting in Plane 1 in 1993. The Consortium withdrew the draft to incorporate changes suggested by Tolkienists, and as of 2005 it remains under consideration.

Both Klingon and the Tolkien scripts have assignments in the ConScript Unicode Registry.

In 2005, the 100,000th character to be entered into the pipeline for standardisation was the MALAYALAM PRASLESHAM. It was encoded based on the contribution by Rachana Akshara Vedi.

The April Fool's Day RFC of 2005 specified two "parody" UTF encodings, UTF-9 and UTF-18.

See also


  • Comparison of Unicode encodings
  • Free software Unicode fonts
  • Mapping of Unicode characters Mapping of Unicode characters

    Unicode [i] reserves 1,114,112 code points.

... 


  • Universal Character Set
  • List of HTML decimal character references
  • Alt codes

References


  • The Complete Manual of Typography, James Felici, Adobe Press; 1st edition, 2002
  • Unicode Demystified: A Practical Programmer's Guide to the Encoding Standard, Richard Gillam, Addison-Wesley Professional; 1st edition, 2002
  • Unicode Explained, Jukka K. Korpela, O'Reilly; 1st edition, 2006

Books about Unicode

  • The Unicode Standard, Version 5.0, Fifth Edition, The Unicode Consortium Unicode Consortium

    The Unicode Consortium, the non-profit organization that coordinates Unicode [i]'s development, has the... 

    , Addison-Wesley Professional, Oct. 27, 2006. ISBN 0-321-48091-0
  • The Unicode Standard, Version 4.0, The Unicode Consortium, Addison-Wesley Professional, Aug. 27, 2003. ISBN 0-321-18578-1


External links


    • Unicode versions: , , , ,
  • Unicode-Wiki with 50.000 gifs in three sizes. English/German.
    • , and
  • and a
  • Uses forms to present groups in list or grid format by hexadecimal Hexadecimal

    In mathematics [i] and computer science [i], base [i]-, hexadecimal, or simply hex, is... 

    .
  • resembles the Windows version. Click a symbol to obtain either the named or numeric code for HTML.
  • a project to standardize part of the Private Use Area for use with artificial script Constructed script

    A constructed script is a new writing system [i] specifically created by an individual or group, rather ... 

    s and artificial languages. An explanation of how to propose character names in Unicode is available here.
  • "A peek at Unicode's soft underbelly" Describes problems requiring resolution. Includes links to Unicode resources.
  • Tim Bray's explains how the different encodings work.
  • Contains lists of word processors with Unicode capability; fonts and characters are grouped by type; characters are presented in lists, not grids.
  • , and a
  • Software engineering Software engineering

    Software En