What are the key principles of RESTful API design?

REST principles: stateless (no server-side session), resource-based URLs (/users, /orders/{id}), HTTP methods for actions (GET read, POST create, PUT update, DELETE remove), standard status codes (200 OK, 201 Created, 404 Not Found), JSON for data exchange. Design practices: use nouns for resources, version APIs (/v1/), pagination for lists, consistent error format, HATEOAS for discoverability. RESTful APIs are the standard for web services.