If your startup is planning to build an app, you're going to need an Application Programming Interface, better known as an “API.” The role of an API is to give your app a set of directions so it can get all the information it needs to interact with your business.

The term API is short for “Application Programming Interface,” and it refers to a piece of code (usually) that lets developers integrate features created by a third party into their apps. While that may sound like a plugin or library, APIs are very different since the creator also typically handles the backend in this case.
A perfect example of the practical use case of an API is Stripe, which is a payment processor that got popular with the rise of drop shipping platforms on the internet. Stripe made it easy for developers to integrate the payment processing feature into their web apps by adding three lines of code.

APIs are reusable; once you create an API for a particular task, you can use it across all the web apps you’ll create in your career. If you choose to open it to the public (like Stripe, for example), anyone around the world can use it, and if you’re strategic enough, you can even proceed to monetize the API.