XPath stands for XML path language. XML Path Language is used as a method to locate and process items in Extensible Markup Language (XML) documents by creating an addressing syntax based on a path through the document’s logical structure. XPath is designed to make writing programming expressions more direct compared to each expression being required to understand XML markup and sequence in a document.
TechTarget explains that XPath is required for Extensible Stylesheet Language Transformations (XSLT) and by XPointer (SML Pointer Language) and utilizes the information abstraction defined in the XML Information Set (Infoset). Furthermore, since XPath does not use XML syntax, it can be applied to non-XML contexts.
It is useful to think of Xpath as a detailed set of directions for finding a particular location. When telling someone how to find the state capitol building in Austin, Texas, for example:
US/TX/Austin/downtown/Congress Ave/11th St.
The most important difference between XPath and other, earlier languages is that XPath details a route using path expressions, instead of just pointing to a particular set or sequence of characters, words or other elements.
XPath takes advantage of path expressions to choose specific nodes or node-sets in an XML document. Path expressions are actually very similar to the expressions you see when working with a traditional computer file system.
Developers have created more than 100 built-in functions to XPath. Types of functions in XPath include functions for string values, numeric values, date and time comparison, node and QName manipulation, sequence manipulation, Boolean values and many others.