They don't. People rarely read Web pages word by word. Instead, they scan the page, picking out single words and sentences. In a recent study, John Morkes and Jakob Nielsen found that 79 per cent of test users always scanned any new page they came across. Only 16 per cent read word by word.
As a result, Web pages have to use scannable text, using
Morkes and Nielsen studied the effect of these guidelines using five different versions of the same website. They measured "usability" through time, errors, memory and site structure. Using all three principles to improve the writing - concise, scannable, and objective - increased usability by 124 percent.
-from Jakob Nielsen, Reading on the Web, Alertbox, October 1, 1997
If you want it read on the web, make your pages "scannable" - that means lots of graphics, headlines, bulleted lists, and the briefest possible text.