API is the acronym for Application Programming Interface, which is a software intermediary that allows two applications to talk to each other. Each time you use an app like Facebook, send an instant message, or check the weather on your phone, you’re using an API.
Application: Think of an application like an ATM. When you walk up to an ATM, you expect it will allow you to access your account and complete a transaction like withdrawing cash. Like an ATM, an app provides a function, but it’s not doing this all by itself—it needs to communicate both with the user, and with the “bank” it’s accessing.
An app deals in inputs and outputs, too. A web, mobile, or back-end application is like a machine that solves a specific problem. The software may be a customer-facing app like a travel booking site, or a back-end app like server software that funnels requests to a database.
Programming: APIs allow the ATM to communicate with your bank. The programming is the engineering part of the app’s software that translates input into output. In other words, it translates your request for cash to the bank’s database, verifies there’s enough cash in your account to withdraw the requested amount, the bank grants permission, then the ATM communicates back to the bank how much you withdrew so that the bank can update your balance.
Interface: A user interface (UI) is how we interact with an application. In the case of the ATM, it’s the screen, keypad, and cash slot—where the input and output occurs. We enter our pin number, punch in how much cash we’d like to withdraw, then take the cash that’s spit out. Interfaces are how we communicate with a machine. With APIs, it’s much the same, only we’re replacing users with software.
Examples of API:
2. YouTube APIs: YouTube API: Google's APIs lets developers integrate YouTube videos and functionality into websites or applications. YouTube APIs include the YouTube Analytics API, YouTube Data API, YouTube Live Streaming API, YouTube Player APIs and others.
3. Flickr API: The Flickr API is used by developers to access the Flick photo sharing community data. The Flickr API consists of a set of callable methods, and some API endpoints