The document discusses the .NET Framework 3.5, which introduced new features like LINQ for querying data, ASP.NET AJAX support, and new protocols in WCF. It provides an overview of what's new in 3.5 compared to previous versions, including LINQ's ability to query nearly any data source, WCF's AJAX and new web protocol support, and full tooling support in Visual Studio 2008. The document also describes what was introduced in .NET Framework 3.0 like WPF, WF, and WCF.