Can you speak about RESTful API principles?

RESTful APIs are built on a set of architectural principles that enable scalable, stateless communication between clients and servers. The core principles are:

1. Statelessness – Each request contains all the information needed to process it; the server does not store session state.
2. Resource identification – Resources are identified by URIs (e.g., /users/123). Clients interact with resources, not with actions.
3. Uniform interface – Standard HTTP methods (GET, POST, PUT, DELETE, PATCH) are used to perform CRUD operations. Responses use standard status codes and media types (JSON, XML).
4. Representation – A resource can have multiple representations; the client negotiates the desired format via Accept headers.
5. Hypermedia as the engine of application state (HATEOAS) – Responses include links to related actions, guiding the client.
6. Caching – Proper use of Cache-Control, ETag, and Last-Modified headers improves performance.

Example: A GET /orders/456 returns a JSON representation of order 456, with links to /orders/456/items and /orders/456/cancel. The server remains stateless, and the client can navigate using these links.