The core of Java(TM) technology, the Java virtual machine is an abstract computing machine that enables the Java(TM) platform to host applications on any computer or operating system without rewriting or recompiling. Anyone interested in designing a language or writing a compiler for the Java virtual machine must have an in-depth understanding of its binary class format and instruction set. If you are programming with the Java programming language, knowledge of the Java virtual machine will give you valuable insight into the Java platform s security capabilities and cross-platform portability. It will increase your understanding of the Java programming language, enabling you to improve the security and performance of your programs.