What is the Hypertext Transfer Protocol?

Hypertext Transfer Protocol (HTTP) is the networking communication language used on the World Wide Web to exchange text, graphics, sound, and other types of data and services. HTTP transfers data between globally linked computers in plain text. A secure version of the Hypertext Transfer Protocol (HTTPS) instructs Web browsers to encrypt communication streams to protect sensitive information. HTTPS is used for all commerce, banking, and other services where a secure link is required.

The invention of HTTP and the World Wide Web is credited to MIT English physicist, Sir Timothy John Berners-Lee (“Tim” Berners-Lee). Berners-Lee proposed the idea in March 1989, and in December 1990, he and his team successfully exchanged data between networked computers using the Hypertext Transfer Protocol.

HTTP operates on the client-server model, where the server is a computer on the Internet hosting a website or data bank, and the client is a computer requesting information from the server. HTTP is actually part of a suite of layered networking protocols. In the networking hierarchy, HTTP is an application layer that runs on top of the dominant transport layer known as Transmission Control Protocol (TCP). TCP is part of the Internet Protocol Suite (IPS) which includes the Internet Protocol (IP) addressing convention used with TCP, the combination of which is referred to as TCP/IP.

Every client and server on the Web is identified by a unique numerical IP address or Uniform Resource Locator (URL). This ensures that requests for data and corresponding responses (datagrams) get routed correctly through the various networks that collectively make up the World Wide Web. Numerical IPs are mapped to an associated name to make the URL easier to remember. Hence, one can enter wisegeek.com in the URL window of a browser, rather than having to remember a string of IP numbers. In a rough analogy, TCP might be thought of as the vehicle or engine that HTTP uses to travel between computers, while IP ensures that the best route will be taken and that the data will arrive at the correct destination.

Like all protocols, the Hypertext Transfer Protocol has evolved over time, changing versions from its original form. Development for HTTP falls to the Internet Engineering Task Force (IETF) and the World Wide Web Consortium. These entities publish Request for Comments (RFCs) detailing new standards, like RFC 2616 of June 1999, delineating HTTP/1.1, the current version most commonly in use.

Secure HTTPS (https:// vs http://) is virtually identical to standard Hypertext Transfer Protocol but for a call to the Web browser to establish an encrypted connection between the server and client. All modern browsers feature point-to-point encryption, occurring automatically and without user intervention when connecting to a site whose address begins with https://. Any data leaving the server or client is encrypted before leaving the computer, and decrypted upon arrival, remaining inscrutable en route.