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 Content-type header. At least that's how it is through version 1.1, but a new HTTP 2.0 under development uses binary requests and responses instead.

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

Specifications

 * RFC 7230: Message Syntax and Routing
 * RFC 7231: Semantics and Content
 * RFC 7232: Conditional Requests
 * RFC 7233: Range Requests
 * RFC 7234: Caching
 * RFC 7235: Authentication
 * RFC 2617: Basic and Digest Access Authentication
 * RFC 2817: Upgrading to TLS Within HTTP/1.1
 * RFC 2818: HTTP Over TLS
 * RFC 2616 (Obsolete; HTTP 1.1; 1999)
 * RFC 2068 (Obsolete; HTTP 1.1; 1997)
 * HTML 0.9 as implemented (W3C)

Links

 * Wikipedia article
 * List of HTTP status codes
 * SPDY proposal (proposed faster HTTP)
 * 451 Unavailable proposed error response for sites blocked by legal action
 * HTTP status codes represented by dogs
 * Compressing the web on how compression is used over HTTP.
 * Malformed servers to test your HTTP client
 * HTTP2 explained
 * How HTTPS works