how does the java virtual machine work?

the java virtual machine or JVM works by providing a virtual set of instructions and facilities that Java programs rely on to run. It then translates these virtual instructions run by the program into instructions that can be run by the underlying system or hardware. As one of the major design goals of Java from its origins was to provide portability of code, this capability allows all java programs to be compiled only for the specifications of the Java Virtual Machine, with the guarantee that those programs will run on any system or hardware platform that has an available Java Virtual Machine that runs on it.