Mono is a platform for running and developing applications based on the ECMA/ISO Standards. Mono is an open source effort led by Novell. Mono provides a complete .NET CLR including compiler and runtime, which can produce and execute CIL bytecode (assemblies), and a .NET class library. . This package includes the Global Assembly Cache (GAC) Tool (gacutil) used by Mono to store shared CIL/.NET (Common Intermediate Language) libraries.