01Overview

In 1989 Berners-Lee submitted a proposal at CERN: link documents with hypertext, identify resources with URIs, transfer them with HTTP. In 1991 the first website went live at CERN. In 1993 the Mosaic browser put images on the same page as text, and the Web exploded.

HTTP was designed to be minimal: a method, headers and a body. State lives on the server; caching, proxies and extensions live in headers. HTTP/2 in 2015 added multiplexing, HTTP/3 in 2022 moved to QUIC — yet the semantics barely changed, which is exactly the strength of layering and backwards compatibility.

02History

  1. 1989

    Berners-Lee's proposal

    The starting point of the Web.

  2. 1991

    The first website

    Online at CERN.

  3. 1993

    The Mosaic browser

    Inline images bring the Web to everyone.

  4. 1996

    HTTP/1.0

    Standardised.

  5. 2015

    HTTP/2

    Multiplexing and header compression.

  6. 2022

    HTTP/3 and QUIC

    A new transport built on UDP.

03Core concepts

URI

A uniform resource identifier: a name for every resource.

Hypertext

Documents referring to each other through links.

Statelessness

Each request stands alone; state is carried by cookies or sessions.

04Hands-on

Do it once — it beats reading it ten times

Write an HTTP/1.1 server in 100 lines that serves a file, then send a raw request with netcat

05Self-check

Say it in your own words first, then open the answer. Whatever you cannot explain is what to review next.

Can you explain "URI"?

A uniform resource identifier: a name for every resource.

Can you explain "Hypertext"?

Documents referring to each other through links.

Can you explain "Statelessness"?

Each request stands alone; state is carried by cookies or sessions.

What problem did it solve, and why was there nothing better at the time?

Go back to the history section: how was this done before, and what did it cost?

If you had to build it today, how would you break it down?

Use the hands-on task above: write a plan of at most three steps before you start.

06Key people

T

Tim Berners-Lee

1955 –

Inventor of the World Wide Web.

M

Marc Andreessen

1971 –

Co-founder of Mosaic and Netscape.

07Further reading

  • Weaving the WebTim Berners-Lee · 1999
  • HTTP: The Definitive GuideGourley & Totty · 2002