.NET assemblies can be categorized into two groups:
shared – common libraries which are used by more than one .NET application;
stand-alone – assemblies used by only one particular .NET application.
The global assembly cache (GAC) is where global shared assemblies are placed. Treat it like a normal folder (or directory) in a shared server from which client machines can retrieve shared assemblies in a distributed environment. You can view the contents of your local machine's GAC using Windows Explorer (go to c:\winnt\assembly – if c:\winnt is where your Windows operating system is installed).
The assembly cache viewer  is installed together with the .NET framework. When you view your GAC using Windows Explorer, ...