- Extensible Mark-up Language.
XML is a specification developed by the W3C and is a mark-up language for structured documents. XML had its roots in specifying and formatting for web documents and web pages, providing a natural development beyond HTML, but it is now also frequently used to provide a common means of data exchange. It supports communication between various companies and applications and is a simplified version of SGML. Despite the various operating system platforms and end devices, data access logic and application logic do not have to be changed.
An XML file is a file that is readable using a standard text editor. The file uses tags to indicate the start and end of blocks, with each opening tag having a matching closing tag (although there are exceptions). Since each tag can contain other tags, XML files provide a means of providing a hierarchy of data. Since each tag has a corresponding closing tag it is possible to read an XML file without understanding what each of the tags means, which is why it is possible to build generic XML parsers.
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