application programming interface (API):
"A set of routines, protocols, and tools for building software applications or for communicating with programs or other systems. A good API makes it easier to develop a program by providing all the building blocks that a programmer needs Although APIs are designed for programmers, they are ultimately good for users because they guarantee that all programs using a common API will have similar interfaces, which makes it easier for users to learn new programs. On the other hand, many enterprise applications vendors provide APIs for integrating other applications with their systems."
