Possible Duplicate:
What should every programmer know about web development?
I've heard rumblings on this site that web developers should be familiarize themselves with HTTP.
What aspects of HTTP is it beneficial to know as a web developer, and why?
Update: This is not an exact duplicate of This is not a duplicate of "What should every programmer know about web development?" I am asking specifically about the HTTP protocol. I am not using HTTP to mean web development in general.