Common Intermediate Language

Common Intermediate Language (CIL), formerly called Microsoft Intermediate Language (MSIL) or Intermediate Language (IL), is the intermediate language binary instruction set defined within the Common Language Infrastructure (CLI) specification. CIL instructions are executed by a CIL-compatible runtime environment such as the Common Language Runtime, and languages that target the CLI compile to CIL. It is an object-oriented, stack-based bytecode, and runtimes typically compile it to native code just in time, although ahead-of-time compilation is also used. During compilation of a CLI language the source code is translated into CIL rather than into platform-specific object code, so that in theory one build can run in any environment that supports the Common Language Infrastructure, such as the .NET runtime on Windows or the cross-platform Mono runtime. CIL was originally known as Microsoft Intermediate Language during the beta releases of the .NET languages and is now officially called CIL because the bytecode was standardized together with C# and the CLI. Tools such as the IL Assembler (ILAsm) and the IL Disassembler (ILDASM) convert between CIL and readable text, which also makes CIL an easy target for reverse engineering and decompilation.