A platform dependent implementation of Java virtual machine (JVM) that is the means by which the byte codes of the Java class libraries and third party applications are executed

Plugins, which enable applets to be run in Web browsers

Java Web Start, which allows Java applications to be efficiently distributed to end users across the Internet

Licensing and documentation.

Core Libraries

Java libraries are the compiled bytecodes of source code developed by the JRE implementor to support application development in Java. Examples of these libraries are:

The core libraries, which include

• Collection libraries that implement data structures such as lists, dictionaries, trees and sets
• XML Processing (Parsing, Transforming, Validating) libraries
• Security
• Internationalization and localization libraries

Integration Libraries

The integration libraries, which allow the application writer to communicate with external systems.

These libraries include

• The Java Database Connectivity (JDBC) API for database access
• Java Naming and Directory Interface (JNDI) for lookup and discovery
• RMI and CORBA for distributed application development
• JMX for managing and monitoring applications

User Interface libraries, which include

• The (heavyweight, or native) Abstract Window Toolkit (AWT), which provides GUI components, the means for laying out those components and the means for handling events from those components
• The (lightweight) Swing libraries, which are built on AWT but provide (non-native) implementations of the AWT widgets
• APIs for audio capture, processing, and playback