XML (eXtensible markup language) is a scripting language that allows programmers to define, or 'markup', specific properties of a document.
The most common use of eXtensible markup language is in XML sitemaps. These are XML files that allow search engines to discover information about the urls on a website that are available to index. XML sitemaps give webmasters control over how search engines view the content of their site.
XML sitemaps are not intended for end users; they are intended only for search engines.