XPath, the XML Path Language, is a query language used to select nodes from an XML document. Additionally, XPath can be used to compute values (e.g., strings, numbers, or boolean values) from the content of an XML document. XPath was defined by the World Wide Web Consortium (W3C). The XPath language is based on a tree representation of the XML document and provides the ability to navigate the tree and select nodes based on various criteria. In common usage, an XPath expression is often simply referred to as XPath. Originally motivated by the desire to provide a common syntax and behavior model between XPointer and XSLT, subsets of the XPath query language are used in other W3C specifications such as XML Schema and XForms.