From MSDN: Download the code for this article: XPathandXSLT.exe(166KB) SUMMARY XPath is emerging as a universal query language. With XPath, you can identify and process a group of related nodes in XML-based data sources. XPath provides an infrastructure that is integral to XML support in the .NET Framework. The XPath navigation model is even used under the hood of the XSLT processor. In this article, the author reviews the implementation details of the XPath navigator and the XSLT processor and includes practical examples such as asynchronous transformations, sorted node-sets, and ASP.NET server-side transformations.