After it has received a request, validated and processed it, and has its thoughts together, the server is ready to send its response.
The only mandatory parts of the response are the HTTP version, the status code, and the status message.
HTTP/1.1 200 OK
Or a multitude of other valid status messages, such as:
HTTP/1.1 404 Not Found
(More information on status codes can be found here)
The HTTP response typically contains a lot more information.
An example of a successful request:
HTTP/1.1 200 OK Cookie: new=cookie%20data X-Robots-Tag: nofollow Connection: Close <html><head><title>HTML page is transferred in the payload</title>
The user is being redirected
HTTP/1.1 302 Found Location: http://www.example.com/new-url Connection: Close
The page could not be found
HTTP/1.1 404 Not Found Connection: Close <html><head><title>A custom 404 page should be sent in the payload</title>Next: Conditional GET >