Definition
Plain language
The well-defined set of commands one piece of software exposes for other software to call.
As stated in the literature
Application Programming Interface — a contract a system exposes for programmatic invocation, including endpoints, payload formats, and expected responses.
Also called: APIs
Why it matters: APIs are how separate software systems plug into each other, and they're the surface that AI agents act on when they 'use tools'.
For example, a weather app calls the National Weather Service API to fetch today's forecast as structured JSON.
Heard on the show
“… if they had a control where the file slated for deletion was something neutral, like a deprecated API doc, and they checked whether the model still found the timestamp loophole to save it. …”Episode 001 — When AI Models Quietly Protect Each Other From Shutdown