What is the difference between the GET, POST, and HEAD methods in HTTP?

GET: Requests data from the server at the specified URI. Data is sent in the query string. It is idempotent and cacheable.

POST: Sends data to the server for processing. Data is sent in the request body. It is not idempotent and not cacheable by default.

HEAD: Requests only the response headers, like GET, but without the response body. Used to obtain metadata about the resource.