What is XPath?
The XML Path Language (XPath) provides a language for addressing parts of an XML document. It is fully described in the W3C XML Path Language (XPath) specification.
XPath was designed to:
- Provide an efficient, compact, logical syntax for referring to path or node tree locations within XML documents.
- Remain an effective language tool for referencing the contents of XML documents separate of any markup used within them.
- Offer a standard library of functions for working with strings, numbers, and Boolean expressions when writing programs that process XML documents.
- Work closely with XSL Transformations (XSLT) and other languages or programming interfaces designed for working with XML.
See Also
XPath Tutorial Application | Concepts | How Do I
Other Resources 
W3C XML Path Language (XPath) Recommendation