The .NET Framework 4 works side by side with older Framework versions. Applications that are based on earlier versions of the Framework will continue to run on the version targeted by default.
What's new in this version:
The Microsoft .NET Framework 4 includes the following new features and improvements:
- Improvements in Common Language Runtime (CLR) and Base Class Library (BCL).
- Innovations in the Visual Basic and C# languages, for example statement lambdas, implicit line continuations, dynamic dispatch, and named/optional parameters.
- Improvements in Data Access and Modeling.
- Enhancements to ASP.NET.
- Improvements in Windows Presentation Foundation (WPF).