XPath is an easy way to address specific parts of an XML document.
XPath, like the Document Object Model (DOM), models an XML document as a tree of nodes. An XPath expression is a mechanism for navigating through and selecting nodes from the XML document. An XPath expression is in a way analogous to a Structured Query Language (SQL) query used to select records from a database.
You can find more about XPath at http://www.w3.org/TR/xpath.
Examples
Use "child::*" to selects all children of the root node.
Use ".//name" to selects all elements having the name "name", descendants of the current node.
You can find more about XPath and query syntax at http://www.w3.org/TR/xpath.