Net framework is used to develop normal desktop/Web application where as compact framework is the one used to develop / run mobile applications. The Compact Framework is also a subset of the .Net framework. If you look at the MSDN documentation for a given framework method, such as this one [http://msdn.microsoft.com/en-us/library/d9hw1as6.aspx] which is the member list for the System.Collection.Generic.List class, you will see small logos next to the method/member names. If you see what looks like a small phone icon, that indicates that method is available on the Compact Framework. As an aside, the smaller "X" icon means it is available on the XNA framework, which is targeted for gaming development on the XBox 360 and Windows.