Here is a brief summary of the software that needs to be setup so as to experiment with Java. JRE - Java Runtime Environment. The famed "Java Virtual Machine" (JVM) on which Java bytecode runs is included in the JRE. Every computer/device that can run Java programs will have the JRE installed. The JVM can be invoked using the "java" command. JDK - Java Development Kit. This is a bundle of software which has all the essential tools needed by a developer to create new Java programs. By Java programs I mean the bytecode that a JVM can run. The most important part of the JDK is the compiler itself; called the "javac". It is the javac that converts the source code (the .java files that is essentially text) to .class files that contain the bytecode. With this background I invite you to patiently go through the nice little tutorial http://docs.oracle.com/javase/tutorial/getStarted/cupojava/win32.html (For Windows users) The above tutorial doesn't intro...