Global Assembly Cache (GAC) is a central repository in the Windows operating system that stores assemblies that are shared by multiple applications. GAC provides several benefits, including improved performance, reduced memory usage, and simplified application deployment. To check if an assembly is installed in the GAC, you can use the gacutil command-line tool.
The gacutil tool provides a number of options for checking GAC contents. The most basic option is to use the -l option to list all assemblies installed in the GAC. You can also use the -i option to install an assembly in the GAC, and the -u option to uninstall an assembly from the GAC.