What types of HTTP headers are there and how do they differ?

HTTP headers can be divided into several types:

• General headers — applicable to both requests and responses, e.g., Cache-Control, Connection.
• Request headers — transmit information about the client and request, e.g., Accept, Authorization, User-Agent.
• Response headers — contain information about the server and response, e.g., Server, Set-Cookie, Content-Type.
• Entity headers — describe the message body, e.g., Content-Length, Content-Encoding.

The differences lie in which part of the HTTP message the headers apply to and what information they carry, which helps in correctly processing requests and responses.