A coding system that allows any type of information to be delivered across the World Wide Web in a structured manner. As a meta-language, it contains rules for constructing other markup languages and allows the creation of tags that expand the type and quantity of information that can be provided about data held in documents. It shares with HTML the common heritage of the SGML (Standard Generalized Markup Language) standard. However, unlike HTML, XML is truly general purpose. The World Wide Web Consortium completed XML in early 1998, and the standard has quickly gained industry-wide, multi-vendor acceptance.