October 20, 2026 · 1 min read
What is an API, explained simply
An API is a restaurant waiter: you order, the kitchen prepares, and you never see what happens behind the scenes. A jargon-free explanation.
- basics
- tech
You keep hearing "we need to plug in an API" and nod along without daring to ask what it is? Here is the explanation, without jargon.
The restaurant picture
In a restaurant, you do not walk into the kitchen. You place your order with the waiter, the kitchen prepares it, and the waiter brings you the dish.
An API is that waiter. One application asks for something ("give me the weather in Lyon"), another service answers ("here it is: 14 °C, cloudy"). The application does not need to know how the weather is calculated.
What it is used for, concretely
- showing a map in your application without building a map;
- taking a payment without storing any card number;
- sending a confirmation e-mail without running a mail server.
Whenever a product "connects to" another one, there is almost always an API in between.
What to remember
An API is a contract: "if you ask me this, this way, I answer you this".
When someone tells you an API "no longer works", it means the contract changed or one of the two sides is no longer answering. And that is often the first place to look when an application starts to misbehave.