REST

Representational State Transfer

HTTP-based API style -- resources, verbs, statelessness.

When you'd see it: API discussions. "REST API" is the most common style of web API.

Why it matters: REST is a convention for structuring web APIs around resources and standard HTTP verbs. Its ubiquity is the value: most services expose a REST API, so the pattern transfers everywhere.

Common mistakes: Calling every HTTP API "RESTful." Many are REST-ish at best. The label gets used loosely, which matters less than whether the API is consistent and well documented.