HTML - The hypertext markup language, the standard 'lingua franca' markup language
invented by Tim Berners-Lee that defines the structure of content that is to be
accessed across the Internet. Also used to define the way text and images are to
be viewed within a Web browser.

In his book Weaving The Web Berners-Lee discusses how HTML was conceived
at the CERN research facilities in Switzerland. A must-read!

One critical component of the founding of the World Wide Web is presentation
language (HTML) that would allow linkages to be made among objects across the
Internet. Tim Berners-Lee presented the URI as the standard for addressing
objects. For completeness on this post, the other two components of the Web's
success were the transfer protocol (HTTP) and the
addressability of objects (URI).