API Application Programming Interface
A set of routines, protocols, and tools used when building software applications. A good API makes it easier to develop a program by providing all the building blocks and enabling a programmer to put the blocks together. Most operating environments, such as MS-Windows, provide an API so that programmers can write applications consistent with the operating environment. Although API are designed for programmers, they are ultimately good for users because they guarantee that all programs using a common API will have similar interfaces.
