What are APIs? - Anecdotes and Metaphors

Background

It can be hard to tell someone what APIs are. Here’s a running list of analogies, metaphors, and other efforts at trying to convey in one or two sentences what APIs are.

Ideas

APIs return a webpage except for machines.
APIs are like the engine of a car. You don’t have to know how it works but rather just turn the key in the ignition and it handles everything underneath.
APIs are like fabric woven together from different sources to make something new.
APIs are like a bartender. It’s what you interact with to get information (what beers do you have on tap?) and functionality (serving you a beer).
APIs are like magic.
APIs are like a contract or a promise.
APIs are the things that you want others to be able to do with your stuff.
APIs are like prayers - you ask for things through them.
APIs are like the world’s best retriever. You say, ‘Fido - go fetch me X’ and he brings you back X.
APIs are like Siri.
APIs are how programs and web services talk to each other.
APIs are like what’s in between a car’s ignition and engine. I don’t know how it works but I know that if I turn the keys in the ignition, the engine will turn on.
UIs are how people use computers. APIs are how computers use computers.
It allows different groups to interoperate without having to interoperate.
When you add an API to a system, the change is similar to moving from CDs to all digital music files.

Posts

Videos

A Project of 18F