API

An API is how programs talk to each other without a human in the middle. You tap a payment card; the app asks the bank’s API. You search flights; the site queries airline APIs. Same idea for AI: a model that can only chat is a brain in a jar until something lets it check a calendar or send a message.

APIs are older than the current AI wave. What changed is that models now sit on the asking side. Someone still has to define the doorway, the permissions, and what “a successful call” looks like.

MCP and similar layers sit above APIs. They do not make APIs obsolete; they try to make many different APIs reachable through one kind of conversation.