XML

It stands for "Extensible Markup Language". XML is used to define documents with a standard format that can be read by any XML-compatible application. The language can be used with HTML pages, but XML itself is not a markup language. 

It can describe items that may be accessed when a Web page loads. Basically, XML allows you to create a database of information without having an actual database. While it is commonly used in Web applications, many other programs can use XML documents as well.