What is JDK, JRE and JVM?

What are JDK, JRE, and JVM:

JDK:- Java Development Kit (in short JDK) is Kit which provides the environment to Develop and execute(run ) the Java program. For eg. You(as Java Developer) are developing an accounting application on your machine, so what do you going to need into your machine to develop and run this desktop app? You are going to need J-D-K for that purpose for this you just need to go to the official website of sun or oracle to download the latest version of JDK into your machine.

Hence, JDK is a kit(or package) which includes two things i) Development Tools(to provide an environment to develop your java programs) and ii) JRE (to execute your java program). JDK is only used by Java Developers.

JRE:- Java Runtime Environment (to say JRE) is an installation package which provides an environment to only run(not develop) the java program(or application)onto your machine. For eg(continuing with the same example) after developing your accounting application, you want to run this application into your client’s machine. Now, in this case, your client only need to run your application into his/her machine so your client should install JRE in-order to run your application into his machine.

Hence, JRE is only used by them who only wants to run the Java Programs i.e. end-users of your system.

JVM:- Java Virtual machine(JVM) is a very important part of both JDK and JRE because it is contained or inbuilt in both. Whatever java program you run using JRE or JDK goes into JVM and JVM is responsible to execute the java program line by line hence it is also known as interpreter(we will discuss interpreter later). Hence you don’t need to install JVM separately into your machine because it is inbuilt into your JDK or JRE installation package.