What is an API (Application Programming Interface)?

An API is all about communication. It is an interface that takes requests and tells the system (application, service, API…) what you want to do and then returns the response back to you. It creates interactivity between applications, databases, and devices to deliver data and create activity that pushes the world at our fingertips. It is like a bridge to communicate in between two systems. APIs are standardized (industry-defined standards for how to define an API).

To give you a familiar example, you arrive at a driving, the operator takes your order and will request the team to prepare it. Once ready, the operator will then give you your order packed (generally, you even pay before). In this case, the operator is an API, he received your order request, communicate with the background team (tells the system what to do: prepare the order). Once the response to that request is transmitted to the API (order prepared and packed), the operator delivers it to you (answer/data from the API).

Now that I’ve whetted your appetite, let’s apply this to a real API example!

You are probably familiar to the process of searching for an hotel into an online comparator website. Just like for your order, you probably know the area where you would like to stay or an idea about the budget you would like to pay. You will have to choose some filters like the area, the number of stars, the budget and so on.

In order to get the search result, the website will interact with its database to check if any hotel is matching your request and what the cost of each might be.

Big comparators can aggregate information from many different hotels. It will then interact with hotels’ API to check information (number of stars, average price budget…). These hotels’ API will then response back with requested information. The comparator can then show up to you.

Now you can understand that it is APIs that makes it possible for us all to book a hotel. The same goes for interactions between applications, data and devices.

There are a few formats that are popular for APIs: REST, SOAP, GraphQL, …