About JDK, JRE and JVM

JDK (Java development kit)

•   Set of programs that enable us to develop our program using java. So, basically whenever you want to start using java we need somethings and everything that we want to need is inside JDK.
  
• Contains JRE (Java Runtime Environment) that is used to run our programs.
•   JRE and JDK contains JVM (Java Virtual Machine).
  
•  JVM executes our java programs on different machines. So, java is independent.

JRE (Java Run-time Environment)

The JRE is on-disk system that takes your Java code, combines it with the necessary libraries, and starts the JVM to execute it. The JRE contains libraries and software that your Java programs need to run.

JVM (Java Virtual Machine)

It is a virtual machine that enables a computer to run Java programs as well as programs written in other language that are also compiled to java bytecode. The JVM is detailed by a specification that formally describes what is required in a JVM implementation.