Application programming interface
Also called API.
An application programming interface, or API, is a defined way for software to request data or actions from other software.
Example
A bot asks a weather API for tomorrow's temperature instead of reading a chart off a web page. The request and the response follow the API's rules.
Why it matters
The API is the contract: which requests exist, what they need, and what comes back. It is not the website's visual page, and it is not a model by itself.
Common confusion
An API is not the Model Context ProtocolModel Context Protocol is an open standard that lets AI applications connect to external tools and information through compatible servers.. MCP is one standard for connecting tools to AI apps. An API is the broader idea of a software contract.
Sources
Updated September 30, 2026.