What is JVM-Java Virtual Machine
A JVM stands for java virtual machine. This is virtual computer or an abstract computer that runs the complied java programs. In fact JVM is a software execution that stands on the top of the real operating system and hardware platform. It serves abstraction among the complied java program and the operating system and hardware. JVM is the very important component of Java architecture & it is the part of the JRE also known as Java Runtime Environment. It makes the cross platform functionality to java.
JVM is a software process which converts the compiled byte code (Java program) to machine code. Byte code is a mediator language among host system and Java source. The mostly programming language like C & Pascal converts the source code into machine code for one particular type of machine because the machine language varies from system to system. Thus compiler generates code for a particular system but the Java compiler produce code for a virtual machine. JVM offers security to java. The programs is written in Java and the source code translated by Java compiler into byte code & after that the JVM converts the byte code into machine code for the computer one wants to run.
Thus the complied program need not to worry about what operating system and hardware, he has to run in, This all handled by the jvm & thus attaining portability. Java programs are complied into byte codes. Jvm can only understand & execute java byte codes.