Extensible Markup Language (XML)
XML is a markup language much like HTML. However, it is different from HTML, which was designed to display data with a focus on how data looks. XML was created to structure, store, and transport data. So, an XML is nothing more than a plain-text document. Any software that can handle plain text can also handle XML.6
The tags used in HTML are predefined. However, XML tags are designed to be self-descriptive and not predefined. Document authors must define their own tags. For example, the tags in Figure 33-7 are not predefined in any XML standard. These tags are defined by the author.
Figure 33-7 A simple XML with ...