JIT (JUST-IN-TIME) is a Compiler before MSIL be executed, it first converted to native code by .NET framework Just In Time(JIT) compiler, which runs on the same System on which the JIT Compiler is executing.

Just-in-time (JIT) is a term that is used to describe any action like compilation or object activation that only happens when it is necessary. This term is associated mostly with software compilation. It is designed because it has features to be accessed on multiple PLATFORMS and it also has high speed.

In Microsoft .NET there are three types of JIT (Just-In-Time) compilers :

• Pre-JIT Compiler: It COMPILES COMPLETE source code into native code in a single compilation cycle. It converts the .NET code from PLATFORM independent state to platform-specific stage.
• Econo JIT Compiler: It compiles only those methods that call at runtime and once these compiles methods are not in use are removed. Econo JIT spends less time compiling so startup latency is lower for interactive applications.
• Normal JIT Compiler: It compiles only those methods that are called at runtime, and after the EXECUTION of these methods is stored in memory, it is commonly referred to as “Jitted”. Methods that are compiled once are not compiled again.