JVM stands for Java Virtual Machine.JVM is platform where Java programs are executed. without JVM we can’t execute java programs. Java program generate output in bytecodes and that bytecodes are executed in JVM. We don’t need to compile java programs again and again for different platforms, because JVM is available for all platforms. Set of Registers,Garbage heap size,method area are specified inside JVM, and JVM tells java programs about these specifications which will be allocated to each program.A Java virtual machine can either interpret the bytecode one instruction at a time (mapping it to a real processor instruction) or the bytecode can be compiled further for the real processor using what is called a just-in-time compiler.