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The
Extensible Markup Language (XML) is a general-purpose
markup language. It is classified as an extensible
language because it allows its users to define their own
tags. Its primary purpose is to facilitate the sharing
of structured data across different information systems,
particularly via the Internet. It is used both to encode
documents and serialize data. In the latter context, it
is comparable with other text-based serialization
languages such as JSON and YAML.
It started as a simplified subset of the Standard
Generalized Markup Language (SGML), and is designed to
be relatively human-legible. By adding semantic
constraints, application languages can be implemented in
XML. These include XHTML,[4] RSS, MathML, GraphML,
Scalable Vector Graphics, MusicXML, and thousands of
others. Moreover, XML is sometimes used as the
specification language for such application languages.
XML is recommended by the World Wide Web Consortium. It
is a fee-free open standard. The W3C recommendation
specifies both the lexical grammar, and the requirements
for parsing. |
