What is JIT Compiler location ?

How and which application is JIT Compiler in windows 10 Latest version of .Net Framework? 

C#, VB.Net or Compiled to MSCIL  then when app runs JIT ( JUST IN TIME ) Compiler compiles and Convert that MSCIL to Native Code ( APP ). What is JIT PE Executable and what it's location in windows 10 .Net Framework. When an IL App runs how JIT Works is this API or SYS OR EXE ?? 

Thanks