API

A pplication P rogram I nterface by which an application program accesses operating system.An API can also provide an interface between a high level language and lower level utilities and services which were written without consideration for the calling conventions supported by compiled languages. Netscape Corporation and Microsoft both provide APIs called NSAPI and ISAPI that essentially extend their web servers, and it provides developers a way to put application code actually within the web server. This means that you don’t have to start up a separate process each time one of these applications is called. And, since that application is always running, it can maintain connections to the database.