XQuery is a query language, which is used for requesting collections of XML data, developed by W3C. XQuery is designed for working with XML, but it does not use XML's syntax. Although there is an XQueryX version that makes use of XML's syntax, it is only seldom used. XQuery is applied versatilely, for example for extraction of information from an XML database, for searching textual documents on the web, for information extraction, etc. Furthermore XQuery allows modifying the data or sort the returned results.

The queries in XQuery can read, return, add a sequence of XML fragments or atomic values from input documents. XQuery relies on other specifications of W3C such as XML 1.1, Namespaces, XPath and XML Schema datatypes. One of the reasons why XQuery is so widely accepted, is that it is supported by all major databases.