HTTP

HTTP (Hypertext Transfer Protocol) is a basic protocol of the World Wide Web, and was one of the original three pillars of the Web as invented by Tim Berners-Lee (the others being URLs and HTML). It consists of a set of standards by which user agents (browsers, indexing robots, etc.) make requests consisting of headers in plain text (and possibly form values and file uploads in various formats) and receive responses including plain-text response headers and content from the Web in a format designated by the Mime-type header.

HTTPS is a secure variant of HTTP which adds SSL encryption.

Links

 * Wikipedia article
 * HTML 0.9 as implemented (W3C)
 * RFC 2616
 * SPDY proposal (proposed faster HTTP)
 * 451 Unavailable proposed error response for sites blocked by legal action