JDK

JDK (Java Development Kit) is a software development package from SUN that implements the basic set of tools needed to write, test and debug Java 1.0 and Java 1.1 applications and applets.

As of Java 1.2 though, the term "JDK" has been dropped and it has been renamed "Java 2 SDK". That is, the Java 2 Software Development Kit. If you want to do Java software development, you need to either download a Java 2 SDK, or else use an ahead-of-time Java compiler like GCJ.

The three Java 2 SDK's available from Sun are J2SE, J2EE, and J2ME.