Unicode and HTML: Difference between revisions

Revision as of 14:48, 15 January 2013

Revision as of 18:12, 15 February 2013

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Web pages authored using '''hypertext markup language''' ([[HTML]]) may contain multilingual text represented with the '''Unicode universal character set'''. Key to the relationship between Unicode and HTML is the relationship between the "document character set" which defines the set of characters that may be present in a HTML document and assigns numbers to them and the "external character encoding" or "charset" used to encode a given document as a sequence of bytes.

In RFC 1866, the initial HTML 2.0 standard, the document character set was defined as ISO-8859-1. It was later extended to [[ISO 10646]] (which is basically equivalent to Unicode) by RFC 20732854. It does not vary between documents of different languages or created on different platforms. The external character encoding is chosen by the author of the document (or the software the author uses to create the document) and determines how the bytes used to store and/or transmit the document map to characters from the document character set. Characters not present in the chosen external character encoding may be represented by character entity references.

The relationship between [[Unicode]] and HTML tends to be a difficult topic for many computer professionals, document authors, and [[World Wide Web|web]] users alike. The accurate representation of text in [[web page]]s from different [[natural language]]s and [[writing system]]s is complicated by the details of [[character encoding]], [[markup language]] syntax, [[Computer font|font]], and varying levels of support by [[web browser]]s.