A .NET programming language like C#, VB.NET etc., not directly COMPILED into EXECUTABLE code; instead, they compile into an intermediate code called Microsoft Intermediate Language (MSIL). SINCE it automatically converts to MSI, so the programmer doesn’t need to be worried about that.

MSIL is similar to Java Byte code. A Java program is compiled into Java Byte code (the .class file) by a Java compiler, the class file is then sent to JVM which converts it into the host machine language.

Along with the Microsoft Intermediate Language MSIL the compiler also produces the MetaData which are contained in the portable executable PE file when the compiler produces MSIL it provides some instruction like  loading, storing, initializing, and calling methods on objects, as well as instructions for arithmetic and logical operations, control flow, direct memory access, exception handling, and other operations

 ADVANTAGES -

• MSIL provides language interoperability as code is written in any .net language is compiled into MSIL.
• Same performance for all .net languages
• It provides support to different runtime environments
• JIT compiler in CLR converts MSIL code into native machine code which is executed by OS