What is HTML?

HTML is a markup language.

Markup Language	Page Description Language
HTML L^AT_EX AAST_EX SGML	PDF PostScript T_EX
Describes the logical structure of the document	Describes the physical location of ink / toner / CRT brightness / etc on the page

Why is logical markup better?

More information: Physical markup contains no information about the actual content of the document. It also assumes certain capabilities of the output device (color, resolution, canvas size, etc).
Describes the document: Logical markup describes the function of each part of the document, leaving the presentation to the output device ("user agent", or browser). That way the presentation can be tuned by the user to match the capabilities of the output device.
Allows appropriate presentation: For example, using a different font to indicate section titles will be of no use to someone on a machine without that font, much less to a blind person using text-to-speech. But marking them up as the appropriate heading level allows even a blind user to jump quickly over uninteresting sections, based on the text in the heading.
Helps automated readers: There are more blind users than you think. Some you may know have names like Alta Vista, Lycos, HotBot, etc. Search engines such as these can, for example, weight heading text more heavily than normal text, to improve the chances of getting a good hit.

Document author: Kevin R. Boyce (email: Kevin.R.Boyce@gsfc.nasa.gov)
This page was last modified on 14-Jan-98 at 4:45 PM