Java Application Programming Interfaces (APIs)
Sun Microsystems’ JavaSoft division, along with its partners, has defined an evolving set of Java Application Programming Interfaces (APIs). These APIs define standard classes and interfaces that you use to build your Java programs.
With these APIs, you can integrate functionality into your program by using standard, proven code that already exists. Sun Microsystems segmented the Java API into a core section and standard extensions to this core. The components of the API themselves are divided into a series of libraries. Some of the libraries contain only core components, some only standard components, and some contain a combination of both.