Hyper Text Transport Protocol.
Sometimes called "How To Transfer Porn". Simple protocol, we're currently up to HTTP/1.1 (see RFC:2616), a lot of people love doing all sorts of unnecessary things over HTTP.
HTTP uses port 80 by default.
The original proposal for what became the WorldWideWeb: http://www.w3.org/History/1989/proposal.html
37 pages link to HTTP: