The primary purpose of xpath language's is to address parts of an XML document. In support of primary purpose, it also provides basic facilities for manipulation of numbers, strings and boolean

XPath is the result of an effort to provide a common semantics and syntax for functionality shared between XSL Transformations(XSLT)and XPointer(XPTR). The primary purpose of XPath is to address all parts of an XML XML document. In support of this primary purpose, it also provides basic facilities for manipulation of numbers, strings and booleans. XPath uses a compact, non-XML syntax to facilitate use of XPath within URIs and XML attribute values. XPath operates on the abstract, logical structure of an XML document, rather than its surface syntax. XPath gets its name from its use of a path notation as in URLs for navigating through the hierarchical structure of an XML document.

Expression is the primary syntactic construct in XPath. An expression matches the production. An expression is evaluated to yield an object, which has one of the four basic types given below:

Expression evaluation occurs with respect to a context.XPTR and XSLT specify how the context is determined for XPath expressions used in XPointer and XSLT respectively. The context consists of:

XPath includes many built-in functions. There are functions for string numeric and string values, date and time comparison, node and QName manipulation, sequence manipulation, Boolean values etc.

XPath is one of the important element in the XSLT standard. Without XPath knowledge you will not be able to create XSLT documents.