A REST API is one common style of API: predictable web requests with predictable shapes. An endpoint is one specific window (customers, invoices, messages), the HTTP method is the action you’re asking for (read, create, update, delete), and the API key is the badge proving you’re allowed at the counter. An SDK packages it all into friendlier code, like handing your assistant a binder of prefilled forms.
Consider the service counter at a well-run office. You don’t wander into the filing room and open cabinets. You go to the right window, ask for the right thing, and use the right form. A REST API is that organized counter for software requests.
Why you care
This matters any time an agent operates inside another system. REST patterns let it work through predictable URLs and request shapes instead of clicking around a screen: “get this client record” beats “open the website and hope the button is still there.” The mental model is an address, an allowed action, a credential, and a response. Clean connections create clean agent work, and messy connections turn every request into a guessing game.