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of meetings, and mail messages—in short, 95 percent of daily life for most people. Hence HTML, the Hypertext Markup Language.

I expected HTML to be the basic warp and weft of the Web, but documents of all types—video, computer-aided design, sound, animation, and executable programs—to be the colored threads that would contain much of the content. It would turn out that HTML would become amazingly popular for the content as well.

HTML is a simple way to represent hypertext. Once the URI of a document tells a browser to talk HTTP to the server, then client and server have to agree on the format of the data they will share, so that it can be broken into packets both will understand. If they both knew WordPerfect files, for example, they could swap WordPerfect documents directly. If not, they could both try to translate to HTML as a default and send documents that way. There were some basic design rules that guided HTML, and some pragmatic, even political, choices. A philosophical rule was that HTML should convey the structure of a hypertext document, but not details of its presentation. This was the only way to get it to display reasonably on any of a very wide variety of different screens and sizes of paper. Since I knew it would be difficult to encourage the whole world to use a new global information system, I wanted to bring on board every group I could. There was a family of markup languages, the standard generalized markup language (SGML), already preferred by some of the world's documentation community and at the time considered the only potential document standard among the hypertext community. I developed HTML to look like a member of that family.

Designing HTML to be based on SGML highlighted one of the themes of the development of the Web: the constant interplay between the diplomatically astute decision and the technically clean thing to do. SGML used a simple system for denoting instructions, or "tags," which was to put a word between angle brackets (such as <h1> to denote the main heading of a page), yet it also had many obscure and strange features that were not well