It is formerly known as WinFX. It is the newer version of .Net Framework platform. It is grants a backward compatibility to Framework version 2.0, and also it includes some new technologies.

What about the new technologies?

Windows Presentation Foundation (WPF, formerly code-named “Avalon”) :
Provides classes for building next-generation smart-client applications that combine UI, documents, and media.

Windows Communication Foundation (WCF, formerly code-named “Indigo”) :
Offers a unified programming model and runtime for building service-oriented applications.

Windows Workflow Foundation (WF) :
Offers a programming model, engine, and tools to build workflow-enabled applications that model business processes.

Windows CardSpace (formerly code-named “InfoCard”) :
Provides a technology for simplifying and improving the safety of working online with personal identity information.

Microsoft .NET Framework 2.0 :
Enables productively building Windows and Web-based applications.

The above technologies represent as new classes WPF, WF, WCF, and CardSpace in System Namespace, and also the core classes from .NET Framework 2.0 remain as they are.

There is a structure diagram of .NET Framework 3.0 below:

Check the below site for further information, the above diagram and some partial content were taken from:

http://msdn2.microsoft.com/en-us/library/aa480198.aspx

Click here to download .NET Framework 3.0 from Microsoft.com

Note: Remember that .NET Framework comes installed with Windows Vista.

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