Question

How does HTTP work?

Answer 1

Pretty expansive question. Which part? Typically HTTP involves establishing a TCP connection between a client and server, then sending a request (typically an HTTP method followed by the HTTP version, followed by a set of HTTP headers, followed by two newlines and a body (if the method requires it), followed by two newlines to indicate the end of the request). The server then sends a response in a similar format, with a set of headers each on their own line, followed by two newlines, followed by the response.

There are significant additional complications, once you introduce things like keep-alive and chunked encodings, but this is the basic interaction in an HTTP exchange.