Why jdk jre and jvm??????? is it needed to devide them and explain??

The program developer needs to develop the code and execute the program i.e, verify the codeand provide a runtime environment 

but the user need not be considered about all those. They are just considered about the execution of the code.

HIERARCHY OF JDK JRE AND JVM :

JDK consists of JRE and JRE consists of JVM

What is JDK:

• JDK stands for java development kit 
• JDK consists of both compiler and JRE 
• For a programmer to write the source code, compile and then execute the program Jdk is used
• JDK is the set of Compiler and JRE

Then what is JRE

• JRE stands for Java runtime environment 
• It has only Jvm 
• That means using JRE we can only execute programs

Note: we can download jre as different application

Now comment what programmers use and what clients use?