Tim Berners-LeeIn 1980, physicist Tim Berners-Lee, who was an independent contractor at CERN, proposed and prototyped ENQUIRE,
a system for CERN researchers to use and share documents. In 1989, Berners-Lee and CERN data systems engineer Robert Cailliau
each submitted separate proposals for an Internet-based hypertext system providing similar functionality. The following year,
they collaborated on a joint proposal, the WorldWideWeb (W3) project, which was accepted by CERN.
 First specifications
The first publicly available description of HTML was a document called HTML Tags, first mentioned on the Internet by Berners-Lee in late 1991. It describes 22 elements comprising the initial, relatively simple design of HTML. Thirteen of these elements still exist in HTML 4. HTML is a text and image formatting language used by internet browsers to dynamically format web pages. The semantics of many of its tags can be traced to early text formatting languages such as runoff. Runoff was developed in the early 1960s for the CTSS (Compatible Time-Sharing System) operating system, and its formatting commands were derived from the commands used by typesetters to manually format documents. Runoff was later incorporated into the UNIX operating system in more advanced formatting programs such as roff, nroff, and troff.
Berners-Lee considered HTML to be, at the time, an application of SGML, but it was not formally defined as such until the mid-1993 publication, by the IETF, of the first proposal for an HTML specification: Berners-Lee and Dan Connolly’s “Hypertext Markup Language (HTML)” Internet-Draft, which included an SGML Document Type Definition to define the grammar. The draft expired after six months, but was notable for its acknowledgment of the NCSA Mosaic browser’s custom tag for embedding in-line images, reflecting the IETF’s philosophy of basing standards on successful prototypes. Similarly, Dave Raggett’s competing Internet-Draft, “HTML+ (Hypertext Markup Format)”, from late 1993, suggested standardizing already-implemented features like tables and fill-out forms.
After the HTML and HTML+ drafts expired in early 1994, the IETF created an HTML Working Group, which in 1995 completed “HTML 2.0”, the first HTML specification intended to be treated as a standard against which future implementations should be based. Published as Request for Comments 1866, HTML 2.0 included ideas from the HTML and HTML+ drafts. There was no “HTML 1.0”; the 2.0 designation was intended to distinguish the new edition from previous drafts.
Further development under the auspices of the IETF was stalled by competing interests. Since 1996, the HTML specifications have been maintained, with input from commercial software vendors, by the World Wide Web Consortium (W3C). However, in 2000, HTML also became an international standard (ISO/IEC 15445:2000). The last HTML specification published by the W3C is the HTML 4.01 Recommendation, published in late 1999. Its issues and errors were last acknowledged by errata published in 2001.