The Java Runtime Environment

• If all you want is to be able to run Java applications and access Java content on the web, you need the Java Runtime Environment, or JRE. It includes the software for the Java virtual machine, as well as the class libraries that various Java programs make use of.
  
  

The Java Development Kit

• If you are a developer and wish to write your own Java programs, or you are seeking to learn the Java language, you need the Java Development Kit, or JDK. In addition to everything in the JRE, it includes the applications that allow you to compile and run your own Java programs and applets.
  
  

Enterprise Edition

• If you are seeking Java software for your business to give to your team of developers, you want the Enterprise Edition, or EE, as opposed to the Standard Edition. It is optimized for large-scale application development.