gacutil is a toll that will list, install, and uninstall 
assemblies in the GAC.

Assemblies are of two types: application private and 
shared. The default is application private and only one 
application uses them. These are the assemblies that are in 
the application folder. A shared assemblies is meant to be 
used by more than one application. It has a globally unique 
name (called a "strong name") and it must be defined in the 
GAC. gacutil will list, install, and uninstall assemblies 
in the GAC.