The key that allow Java to solve both the security and the porability problems is that the output of a Java compiler is not executable code . Rather , it is bytecode . Bytecode is a highly optimized set of instruction designed to be executed by the java run -time system , which is called the JAVA VIRTUAL MACHINE (JVM) . In essence, the original JVM was designed as an interpreter for bytecode . This may come as a bit of a surprise since many modern language are designed to be compiled into executable code because of performance conerns.
