Question

What does API (Application Programming Interface) mean?

Do programmers have to refer API’s (Facebook social networking API site), when developing site in other platforms?

I don’t know anything about coding, so I would like some examples in addition to a definition, especially with context to iPhone.

Answer 1

An API is a system designed by programmers for programmers.

Here’s the definition from the Simple English Wikipedia:

An Application Programming Interface
(API) is a set of functions,
procedures, methods or classes used by
computer programs to request services
from the operating system, software
libraries or any other service
providers running on the computer. A
computer programmer uses the words in
the API to make application programs.
Types of API include web services API
like the Twitter API, which allows
programs to use the API to receive
updates on tweets.

APIs can have to do with websites, like the Twitter example, in which programmers use the Twitter API to interact with Twitter, like finding tweets by a certain user or tweeting on a user’s behalf. The Facebook API works similarly: it a system that Facebook created that I can use to access certain data on Facebook.

APIs can also be used to interact with systems in general. In the case of the iPhone, there is the language of Objective-C, and the iPhone API is a set of Objective-C methods built by Apple that allow a developer’s app to interact with the iPhone. For example, the iPhone API includes methods for responding to fingers on the touch screen, and methods for drawing to the screen.