An application programming interface (API) is a set of routines, protocols, and tools for building software applications. An API often serves as the middleman that helps two programs communicate with one another. Most companies have open-source APIs so other software developers can build their products off of their service.
One of the most common examples of explaining how APIs work is the “restaurant scenario.” When you’re at a restaurant, the waiter acts as the middleman who takes your requests and tells the kitchen what you want. In this scenario, the waiter is acting as an API, the messenger who helps two systems communicate – you, the client, and the kitchen, the system. When your food is ready, the waiter returns the food/response to you. Without the waiter, the restaurant’s service wouldn’t work. Just like how many applications wouldn’t work if there weren’t APIs helping systems communicate with one another.
Google Maps – Google Maps API allow developers to embed amps into their own applications.
YouTube – YouTube’s API allows developers to integrate video into their websites.
Instagram – Instagram’s API allows developers to incorporate photos, pull tags, and view trending photos on their own applications.