The Full form of XML is Extensible Markup Language. XML is a markup language that was designed to transport and store data in a specific format that can be processed by human and machine intelligence. Extensible Markup Language defines a set of rules to encode documents in that specific format. It is language and platform independent.
As Hypertext Markup Language (HTML), the basic format for Web pages does not allow the definition of new text elements; that is, it is not extensible and therefore, XML began to be developed in the 1990s. XML is a simplified form of Standard Generalized Markup Language (SGML) intended for documents that are published on the Web. The main goals of XML design are Simplicity, Generality, and Usability.