When compiling to managed code, the compiler translates 
your source code into Microsoft intermediate language 
(MSIL), which is a CPU-independent set of instructions that 
can be efficiently converted to native code. MSIL includes 
instructions for 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. 
Before code can be run, MSIL must be converted to CPU-
specific code, usually by a just-in-time (JIT) compiler. 
Because the common language runtime supplies one or more 
JIT compilers for each computer architecture it supports, 
the same set of MSIL can be JIT-compiled and run on any 
supported architecture. When a compiler produces MSIL, it 
also produces metadata. Metadata describes the types in 
your code, including the definition of each type, the 
signatures of each type’s members, the members that your 
code references, and other data that the runtime uses at 
execution time. The MSIL and metadata are contained in a 
portable executable (PE) file that is based on and extends 
the published Microsoft PE and common object file format 
(COFF) used historically for executable content. This file 
format, which accommodates MSIL or native code as well as 
metadata, enables the operating system to recognize common 
language runtime images. The presence of metadata in the 
file along with the MSIL enables your code to describe 
itself, which means that there is no need for type 
libraries or Interface Definition Language (IDL). The 
runtime locates and extracts the metadata from the file as 
needed during execution

It is cpu independent language.It is only understand by CLR.
due this language(MSIL) vb.net application can run on any 
platform on which .net framework is present.

It is a Microsoft Intermediatary Language which helps to 
convert programming language into machine's native language 
at the time of compilation.

MSIL IS Microsoft Intermediate language.It manage code when
compiling. the compiler translate your source code into
microsoft intermediate language.It must be converted cpu
specific code, usually by a jit(just in time)