What is REST, its methods, and their differences.

REST (Representational State Transfer) is an architectural style for creating web services that uses standard HTTP methods to interact with resources.

The main HTTP methods in REST and their purposes:

• GET — retrieve a resource or a list of resources. Does not change the server's state.
• POST — create a new resource.
• PUT — update an existing resource or create it if it does not exist.
• PATCH — partially update a resource.
• DELETE — delete a resource.

Differences in methods lie in how they affect the server's state and idempotency:

• GET, PUT, DELETE — are idempotent (repeated calls do not change the result).
• POST — is not idempotent (each call can create a new resource).

Example: a GET request to /users/123 will return data for the user with id 123, while a POST to /users will create a new user.