Extensible Markup Language (XML) is a markup language that is used to encode and structure data. It is a flexible and extensible language, and can be used to represent data in a wide range of formats, including text, numbers, and multimedia. XML is designed to be self-describing, which means that the structure and meaning of the data it encodes are contained within the document itself. This makes it easy to process and interpret XML data, and to exchange it between different systems. XML is often used as a format for storing and exchanging data between databases, applications, and web services.