There are four ways to install an assembly into the global assembly cache:
Using the Global Assembly Cache tool (Gacutil.exe).
You can use Gacutil.exe to add strong-named assemblies to the global assembly cache and to view the contents of the global assembly cache.
Gacutil.exe is only for development purposes and should not be used to install production assemblies into the global assembly cache.
Using Microsoft Windows Installer 2.0.
This is the recommended and most common way to add assemblies to the global assembly cache. The installer provides reference counting of assemblies in the global assembly cache, plus other benefits.
Using a Windows shell extension provided by the .NET Framework SDK called the Assembly Cache Viewer (Shfusion.dll).
The shell extension allows you to drag assemblies into the global assembly cache.
Using the .NET Framework Configuration Tool (Mscorcfg.msc).
The .NET Framework Configuration Tool (Mscorcfg.msc) allows you to view the global assembly cache and add new assemblies to the cache.
At the command prompt, type the following command:
gacutil –I <assembly name>
In this command, assembly name is the name of the assembly to install in the global assembly cache.
The following example installs an assembly with the file name hello.dll into the global assembly cache.
gacutil -i hello.dll