XML in Semantic web

Extensible Markup Language (XML) is a subset of SGML (the Standard Generalized Markup Language), i.e. it is totally compatible with SGML. But it is simple and flexible. It’s original aim to tackle the problems of large-scale electronic publishing. However, it is also very important in data exchange on the Web. Despite its name, XML is not a markup language but a set of rules to build markup languages.