What is GAC

GAC (Global Assembly Cache) is used where shared .NET assembly reside.GAC is used in the following situations :-

1. If the application has to be shared among several application.

2. If the assembly has some special security requirements like only administrators
can remove the assembly.If the assembly is private then a simple delete of
assembly the assembly file will remove the assembly.

Note:-Registering .NET assembly in GAC can lead to the old problem of DLL hell.
Where COM version was stored in central registry.So GAC should be used when
absolutely necessary.