The figure below explains the lifecycle of a Java Program. In words, the figure can be explained as: A Java program is written using either a Text Editor like Textpad or an IDE like Eclipse and is saved as a .java file. (Program.java) The .java file is then compiled using Java compiler and a .class file is obtained from it. (Program.class) The .class file is now portable and can be used to run this Java program in any platform. Class file (Program.class) is interpreted by the JVM installed on a particular platform. JVM is part of the JRE software.