What is an API?

An API (Application Programming Interface) is simply some software that sends information back and forth between a website or app and a user.

Imagine you go to a restaurant. You check the menu and place the order. This order needs to be sent to the kitchen. Hence, you place the order through a waiter. The waiter takes your order to the kitchen and brings back your food from the kitchen.

In this example, the menu is your application. You are sending request by placing your order. Waiter act as the API which is the intermediary who takes your request to the kitchen — the back-end system. You get the food or the response from the kitchen through the waiter or the API.

Image Source Credit: Celeste Layne - Medium.com

Why Are APIs Important?

The first reason why APIs matter is that your site, app or service isn’t doing anything without them. You need them to process an order and confirm payment if you are selling anything. You need them to collect data if that is the goal of your solution. A service can’t just sit there doing nothing. The Internet is too interactive for that. The second reason is that APIs these days are packaged as products that developers can use to build your site or app or even to add value or a new way to deliver value for the systems you build.

Let’s say you wanted to sell products from Amazon on your site. You could build an entire architecture to do it. But that would take a ton of time and effort. Plus whenever Amazon updated their site you’d have to do it all over again. Instead Amazon will provide you with their API. You simply place the API in your code. Then when the price changes it changes on your site. It is displayed correctly. If Amazon changes their site in any way it’s updated on your end. In fact, Amazon almost certainly created the modern API eco-system when they realized the value inherent in common components everybody could use.

There are a ton of APIs like that out there. They are built so that you can create a website or app and link to their websites. So if you want to have Google Maps in your app you don’t have to design it yourself. You can take the API and have the map - and all its updates - in your app forever.

All in all APIs are easy to understand. They transmit data back and forth in the background. They make the web interactive and useful for people to use. They mean you can interact with apps, smart TV services, your car and more and yet you never see them. They simply work.