XML ( Extensible Markup Language) is a simple, flexible, powerful, and portable markup language developed by the World Wide Web Consortium (W3C). XML contains human-readable data combined with human-readable metadata. That is, XML files contain regular text, so you can read them. They also contain both data and descriptions of that data.
XML provides a simple format for describing data. XML does not contain any predefined tags, unlike HTML (Hypertext Markup Language). You can create your own tags in XML. Therefore, depending on the need of your application, you can create specialized tags. For example, for a publishing business, you can create tags such as Author, Title, ISBN, and so on. Because the structure of XML is simple and extensible, it is useful in applications such as exchange of information between organizations, Web site publishing, object serialization, remote procedure calls, and so on.