An Acronym (yet another TLA) for eXtensible Markup Language.

A W3C-maintained standard for a marginally human read-/editable MarkupLanguage. It is a simplified decendant the extremely comprehensive SGML standard for which hardly a single fully compliant parser was ever written. Many of its features, even implemented ones, are hardly used. On the other hand, it lacks various useful features. XML was designed to address these shortcomings while reducing the language specification to a small set of rules in order to be easily and consistently parsable. It lacks features such as CONCUR but adds others such as NameSpaces (as good an idea in a MarkupLanguage as they are in a ProgrammingLanguage).

XML is specialised using a DTD, an XML Schema, or a RelaxNG? schema to describe the structure of data within a XML document. Each specialisation is actually a new language for marking up a particular type of data. Thus DocBook is a specialisation for marking up the text of books, XHTML is a specialisation for marking up web pages, MathML? is a specialisation for marking up mathematical equations, tables and formulae and XSLT is a specialisation for marking up a programming language (a functional programming language expressed in XML).

See also:


XML is like:

  • SGML without configurability
  • HTML without forgivingness
  • LISP without functions
  • CSV without flatness
  • PDF without Acrobat
  • ASN.1 without binary encodings
  • EDI without commercial semantics
  • RTF without word-processing semantics
  • CORBA without tight coupling
  • ZIP without compression or packaging
  • MacromediaFlash without the multimedia
  • A database without a RDBMS or DDL? or DML? or SQL or a formal model
  • A MIME header which does not evaporate
  • Morse code with more characters
  • Unicode with more control characters
  • A mean spoilsport, depriving programmers the fun of inventing their own syntaxes during work hours
  • The first step in Mao's journey of a thousand miles
  • The intersection of James Clark and Oracle
  • The common ground between Simon St. L and Henry Thomson
  • The secret love child of Uche and Elliotte
  • MicrosoftCorporation's secret weapon against Sun's OpenOffice
  • Sun's secret weapon against MicrosoftCorporation's Office
  • The town bicycle

– Rick Jelliffe