The REST API Design Handbook

by George Reese

the four main methods: GET Fetches a representation of the named resource without any side-effects. Two consecutive GETs should always provide the same result. POST Creates a new resource from an external representation at the named point. A POST is not for making changes to an existing object. PUT Executes updates to a resource from an external representation of that resource. DELETE Deletes the target resource from the system. There are other methods available, but they are generally not strictly necessary to create a complete REST API. In fact, not every resource will be impacted by the four core methods.

These map exactly to CRUD operations.