The Java Virtual Machine

• Provides hardware platform specifications
• Reads compiled byte codes that are platform-independent
• Is implemented as software or hardware
• Is implemented in a Java technology development tool or a Web browser

JVM provides definitions for the:
• Instruction set (central processing unit [CPU])
• Register set
• Class file format
• Stack
• Garbage-collected heap
• Memory area
• Fatal error reporting
• High-precision timing support

• The majority of type checking is done when the code is compiled.
• Implementation of the JVM approved by Sun Microsystems must be able to run any compliant class file.
• The JVM executes on multiple operating environments