Definition of API

API is the application program interface that exists between the application programs and the operating system. It is the source code that operating systems use to support the functioning of computer programs. It supports the requests made for services required for the application programs to function properly. The API increases the capabilities of Web servers and it is popular with programmers who write applications that are interactive with other applications.

An API server is a set of programs that are integrated collectively into a Web server so that it is capable of interacting with the API. A server API, created by software developers who write the programs, is a published interface. The programs actually become part of the server. Some of the more common server APIs along with the servers that are supported by them include: Netscape Commerce and Enterprise Server, NSAPI, ISAPI, Microsoft Internet Information Server, and WSAPI, O’Reilly Website and Website Pro.

External links:

• Wikipedia explanation of API
• Webopedia explanation of API
• About,.com Definition
• About.com article about API