The Unicode Charset — Introduction

The Unicode character encoding scheme can be understood as a standardized extension of the simple 7bit ASCII charset. While ASCII just encodes 95 characters, 128 less 33 control characters, the aim of Unicode is to encode virtually all characters existing not only in today's languages, but also in dead languages, general symbols, typographical symbols (dingbats), diacritical marks, and (mathematical) formulas. As of today Unicode is able to encode the sheer amount of 1,114,112 characters.

What Unicode does not do is to describe how a character should look like, that is, it does not define any glyph. Unicode just defines an abstract character and allocates a code point to this character. Such a definition may be LATIN CAPITAL LETTER A WITH DIAERESIS, the corresponding code point is 196dez or 00C4hex. How this character is rendered on screen or printed on paper depends on the font used, as the following illustration shows.

The extended ASCII character encoding scheme and codepages use one byte to encode characters. Using two byte instead of one leads to 65,536 possible code points. This range is called the Basic Multilingual Plain, BMP, in Unicode. To be able to encode more characters, three or even four byte are neccessary, which would lead to a theoretical 2³² = 4,294,967,296 encodable characters.

Unicode is transformed into a byte sequence using the Unicode Transformation Format, UTF. The byte sequence is then transferred to programmes for further processing. There exist a couple of UTF formats: UTF-5, UTF-7, UTF-8, UTF-16 and UTF-32. The most important of these is UTF-8, which is understood by most browsers, word-processing programmes etc. The term UTF-8 is also used in character encoding declarations to denote the use of Unicode character encoding.

As mentioned before a font is neccessary to transform the abstract characters into glyphs. A font maps each code-point to a glyph which means, that a fully Unicode-supporting font should be able to map more than 60,000 characters. However, most fonts only cover a very limited range, mainly code-points 31 to 255. The following chart lists fonts which are able to display a wider range of characters. Font examples are shown when clicking on a font's name.

Unicode Fonts & Sources

Font	Number of Characters	Generic Font Family	Homepage/Information	Size	Download[1]
follow these links to view a font example
[1] The fonts listed in this chart are, with the exception of Code2000, free of charge for private use. You should consult the homepage of the providers when considering commercial usage of these fonts.
Bitstream CyberBase	1249	serif	Netscape - Public FTP Server	171kB
Bitstream CyberBit	29934	serif	Netscape - Public FTP Server	6227kB
APL Unicode Font Extended - SImPL	~1000	monospace	Vector.org - APL-Fonts	209kB
Code2000	34810	serif	http://home.att.net/~jameskass/ Shareware	1219kB
Fixedsys Excelsior	>4100	monospace	http://www.fixedsys.org/	233kB
Gentium	1387	serif	SIL International - NRSI - Gentium	601kB
Lucida Sans Unicode	1776	sans-serif	Dept. of Phonetics & Linguistics University College London	298kB
Titus Cyberbit Basic	9779	serif	TITUS	808kB
Arial	1320	sans-serif	SourceForge-Net: Smart package of Microsoft's core fonts	542kB
Times New Roman	1320	serif		647kB
Courier New	1318	monospace		632kB
Verdana	893	sans-serif		344kB
Andale Mono	659	monospace		194kB
Arial Black	669	sans-serif		165kB
Comic Sans MS	574	kursiv		241kB
Georgia	585	serif		384kB
Impact	661	fantasy		170kB
Trebuchet MS	576	sans-serif		349kB
Arial Unicode MS	51180	sans-serif	distributed with MS Office 2000, Office XP and Publisher 2002

A note on the term charset:
The W3C recommends using the term character encoding instead of the terms charset and character set:
Specifications SHOULD avoid using the terms 'character set' and 'charset' to refer to a character encoding, except when the latter is used to refer to the MIME charset parameter or its IANA-registered values. The term 'character encoding', or in specific cases the terms 'character encoding form' or 'character encoding scheme', are RECOMMENDED.