API (application programming interface)
An API is a defined way for one program to ask another for something. AI companies offer APIs so developers can send text to a model from their own apps and pay per use, usually per token.
In one line, for a 12-year-old
An API is a doorway that lets one app talk to another app's brain.
An example
A recipe website sends your list of ingredients to an AI model through its API and shows you dinner ideas.
Why it matters to people
When an app uses an AI company's API, your words may pass to that company. A good privacy policy names those providers.