Application Programming Interfaces (APIs)
Application programming interfaces (APIs) are sets of instructions that describe the method in which a particular task is to be performed. A good example of an API in action is when you log in to Instagram with your Twitter account, post a photo to Facebook from your phone or get information about when and where a movie is playing through a mobile app on your phone.
A simple API that I built (theoretically) in mashape to retrieve info about a film playing at SIFF reads as follows:
Film Screening Event: get information about a single film event
In addition to simple GET commands (read only), there are also GET & PUSH (read and write) and PUSH (write only) commands. Most typically, APIs are used with web services and tools, usually for Web 2.0 and social connectivity tasks.