I tried to think of everything a web developer should know about HTTP, then recorded those things into a Pluralsight course: HTTP Fundamentals.
In the course you'll look at HTTP messages, message headers, cookies, caching, and authentication protocols. You'll see HTTP work from a low level TCP/IP perspective using Wireshark and System.Net.Sockets. But, you'll also see HTTP from a higher level architectural perspective and learn to think of the Web as an extension of your application's architecture.
Persistent connections, proxy servers, and content negotiation – it's all there. Give it a try.
