This chapter begins with the introduction of the classes provided by the .NET Framework Library to work with Extensible Markup Language (XML) documents. This chapter discusses how to read from and write to XML documents using the .NET Framework Library classes. After that it discusses how to navigate through XML documents. The chapter also discusses XML transformations. In addition, this chapter covers the relationship between ADO.NET and XML and shows how to mix them up and use rich ADO.NET database components to display and manipulate XML data. Finally, this chapter covers the XPathNavigator class, which navigates XML documents.