What are differences between JVM,JRE and JDK ?

What are differences between JVM,JRE and JDK ?

JVM
 JVM is an acronym for Java Virtual Machine.it is an abstract machine that provides runtime environment in which java bytecode can be executed.
 
 The JVM performs following main tasks:
 1 Loads code
 2 Verifies code
 3 Executes code
 4 Provides runtime environment
 
 JRE
 1 JRE is an acronym for Java Runtime Environment.It is used to provide runtime environment.It      physically exists.
 2 JRE is an implementation of the Java Virtual Machine which actually executes Java programs.
 3 Java Runtime Environment is a plug-in needed for running Java programs.
 4 JRE is smaller than the JDK so it needs less disk space.
 5JRE includes the JVM, Core libraries and other additional components to run applications and applets  written in Java.
 JDK
 1JDK is a bundle of software that is used to develop Java based applications.
 2Java Development Kit is needed for developing Java applications.
 3JDK needs more disk space as it contains the JRE along with various development tools.
 4 JDK includes the JRE, set of API classes, Java compiler, Webstart and additional files needed to  write Java applets and applications.