05 · Getting Models to Act
API
Application Programming Interface
A defined interface one program uses to request data or actions from another. Many hosted models are reached through APIs, while open-weight models can also run locally or behind an API you operate yourself.
Concrete example
An app sends your prompt to OpenAI's API and displays the reply — you never touch the model itself.
Why it matters
Nearly all AI reaches you through an API — and it's the same mechanism that lets models call other software.