JDK & JRE & JVM & JIT

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Life Cycle:
      Java Code -> JDK -> Byte Code -> JVM (JIT ) <->JRE

JDK (Java Development Kit):
   It is a Platform dependent software. It is provide tools and binaries to execute and debug the Java Programs. So it is only needed when you are developing the code in your system.

 JDK = JRE + Development Tool


JRE (Java Run time Environment):
  It is responsible to provide platform to run the Java Program. If you want to run the Java Program you must installed JRE. 
 JRE = JVM +Libraries

JVM (Java Virtual Machine):
  When we run the program JRE is responsible to convert the Java code in to Byte code (Byte code is nothing but Boolean value eg. 0,1). JVM provides core java functions like Memory Management, Security, Garbarage Collection etc. This independence from Hardware and OS, this is what Java write once run anywhere.
JVM = Load + Verify + Execute Byte Code + Allocate Memory for OS

JIT (Just In Time Compiler):
  It is the component of JRE. It improves the performance of Java Application at Run time. When JVM  affect performance, It is choosing like you are a java developer or end user.

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