Global Assembly Cache
Global assembly cache is the designated storage location for assemblies to be shared by several applications on a device. All devices with common language runtime (CLR) installed have a global assembly cache. It stores all assemblies that shared by multiple applications on a device.
You can use either of two methods to install an assembly into the global assembly cache:
You can use an installer specifically designed for the global assembly cache. According to MDN, this is the preferred option to deploy assemblies into the global assembly cache.
You can also use a developer tool called the global assembly cache tool provided by the Windows Software Development Kit to install assemblies into the GAC.
MDN suggests using Windows Installer to deploy assemblies into the global assembly cache in deployment scenarios. By the same token you should only use the Global Assembly Cache tool in development scenarios, as the tool doesn’t offer assembly reference counting or other useful features in Windows Installer.