W3C Hypertext Transfer Protocol Overview
This is the overview materials related to the W3C HTTP activity, one of the W3C Architecture domain activities. HTTP has been in use by the World Wide Web since 1990 and its use has increased steadily over the years, mainly because it has proven useful as a generic middleware protocol.

RFC2068 - HTTP/1.1 Specification
HTTP/1.1 is the latest specification from the World Wide Web Consortium.

RFC1945 - HTTP/1.0 Specification
Despite the improvements made in version 1.1, HTTP/1.0 is still widely used around the Internet.

RFC2145 - Use and Interpretation of HTTP Version Numbers
This document tries to clarify the intentions of the specs for HTTP versions 1.0 and 1.1. The aim is to avoid confusion regarding the use and interpretation of each.

Hypertext Transfer Protocol - Next Generation Overview
The purpose of the HTTP-NG Project is to tackle current HTTP deficiencies by using sound engineering practices.

rproxy -- rsync in http
HTTP extensions to allow download of only the changes between cached and current versions of a page,

PEP
W3C working draft of an Extension Mechanism for HTTP.

Cookies - HTTP
Information on cookies including some background info, articles, technical specifications, and what consumer groups think.

An Analysis of HTTP Performance
Paper by Joe Touch, John Heidemann, and Katia Obraczka of the USC/Information Sciences Institute.

Improving HTTP Latency
Paper by Venkata N. Padmanabhan and Jeffrey C. Mogul.

Clarifying the Fundamentals of HTTP
Analysis of HTTP/1.1, identification of its failures, and suggestions for improvement. By Jeffrey C. Mogul of Compaq Research.