What is the difference between a request sent to the server and the response received from it?

A request is a message sent by the client to the server to retrieve data or perform an action. It contains a method (GET, POST, etc.), URL, headers, and possibly a body with data.

A response is a message returned by the server in reply to the request. It contains a status code (e.g., 200 OK), headers, and a body with data (e.g., HTML, JSON).

The main difference is that a request initiates interaction and describes what the client wants to get or do, while a response contains the result of executing that request from the server.