Different views of the GAC

Each computer wherein the common language runtime is installed has a machine-wide code cache called the Global Assembly Cache. This Global Assembly Cache stores .NET assemblies specifically designated to be shared by several applications on that computer.

• Shell Extension [SHFusion.dll] (default)
  Go to Run Window in Start Menu : "%systemroot%\assembly".
  
• GAC Directory Browsing

Go to Run Window in Start Menu : "%systemroot%\assembly\GAC".

The first view is the default view, but the second view helps you to find/locate the real assembly that you might need! There is also a registry modification possible to override the default view to the second view :

• Open Registry with regedit, browse to HKLM\Software\Microsoft\Fusion
• Add a REG_DWORD value named "DisableCacheViewer"' and set it's value to 1

Developers also face a very common issue in Visual Studio when they want to add a reference to an assembly in the Global Assembly Cache. The problem is that the Add Reference dialog box is path-based and does not enumerate the components from the GAC. See this Knowledge Base Article for a possible workaround.