What Is an API? A Plain-English Guide for Beginners

An API (application programming interface) is a way for one program to ask another for something. Think of a restaurant menu: you do not walk into the kitchen. You pick an item by name, and the kitchen sends back exactly that item.

The three parts you will see everywhere

A URL that says what you want, such as /v1/names/3.
A method that says what you want to do. GET means "give me data."
A response, usually JSON, plus a status code like 200 (OK) or 404 (not found).

Try it right now

Open the API Lab and press a button. You just made a real API request. Nothing to install.

Why it matters

Almost every app you use is a pile of small APIs talking to each other: weather, maps, payments, login. Once you can read one, you can read them all.

Challenge

Press GET /v1/get/name in the API Lab until you have seen 5 different names. Write down each id. What do you notice?

Show the answer

The ids are whole numbers from 1 to 12, and the same id always goes with the same name (id 7 is always Katherine). Only the random pick changes from request to request, not the data behind it.