XML stands for EXtensible Markup Language. XML is not a language (which is by definition fixed) but a meta-language. XML is a set of rules, that a language must respect in order to be XML conformant. Therefore you can define your own mark-up language, and make it to evolve at your envy.This informs us that the structuring elements of that language will be tags, like used in HTML: a tag name enclosed in brackets: <ATag>.XML is a language to define other languages: it is in fact a meta-language.
