XML (Extensible Markup Language) is a new kind of Web language developed by W3C to follow the development of Internet, and it is a subset of SGML which was developed and standardized by the International Organization for Standards.

• XML(Extensible Markup Language，可扩展标记语言)是W3C(World Wide Web Consortium)为适应Internet的发展而推出的新型Web语言，是ISO(国际标准化组织)所制订的SGML(Standard Generalized Markup Language，标准通用标记语言)的一个子集。