API
The menu of things one program lets another program ask for.
An API (Application Programming Interface) is a set of rules for how two programs talk. One side publishes what you can ask for and in what format; the other side sends requests and gets answers. You never see the kitchen, only the menu and the dishes.
On the web, most APIs work over HTTP: your app sends a request to a URL like /weather?city=Rosario and receives data back, usually as JSON. Maps in a food delivery app, the login with Google button, a chatbot inside a website: all APIs.
APIs are how companies sell software to other software. AWS, Stripe, and Anthropic are, at their core, collections of APIs with a bill attached.
Keep in mind
- An API defines what you can ask, how to ask it, and what you get back.
- Web APIs usually use HTTP and return JSON.
- An API key is the credential that says who is asking (and who pays).
