The .Net Framework is a stack. At the bottom is the "Common Language Runtime" which itself runs on the native computer hardware. Above that sits the Base Class Library with WinForms (Desktop windows programming), ASP.Net (Web programming) and ADO.Net (Data access). This is the .Net Framework 2.0. The .Net Framework 3.0 adds WPF (Windows Presentation Foundation(, WCF (Windows Coummunication Foundation), WF (Windows Workflow Foundation) and Windows CardSpace. Each new version of the .Net framework adds new functionality on top of the old one. .E.g., Net Framework 3.5 has LINQ, and .Net Framework 4.5 contains .Net for Windows Store (Metro style) apps.