what is an api?

The term API is used in a huge number of situations. For people, like myself, who have not been coding for years, this can be confusing. When you’re just getting started coding, it feels like everything these days is an API… even if you aren’t quite sure what that means.

Kristopher Selbekk and Caroline Odden offer one of the best definitions I’ve found in their article The 10 Component Commandments:

An API - or Application Programming Interface - is basically where two pieces of code meet. It’s the contact surface between your code and the rest of the world. We call this contact surface an interface. It’s a defined set of actions or data points you can interact with.

To me, this definition gets at the crux of what an API is (really the surface area of your code that’s available for others to touch) which makes it clear why it’s bandied about so often! It applies as well to end points on a server as a function signature!