Several devices, from portable computers and personal digital assistants (PDAs) to mobile phones and video cameras, use liquid crystal display (LCD) technology to render images on a screen. Before these innovations existed, the smallest level of detail that a computer could use was a single pixel. With ClearType font technology, LCD monitors now can display features of text as small as a fraction of a pixel in width.
The result is that the words on a computer screen now look almost as sharp and clear as those printed on a piece of paper. ClearType improves readability of text on LCD displays so that words on the screen appear almost as sharp and clear as words on a printed page. Resolution improvements also increase the sharpness of tiny details in text that is displayed. This makes it easier for the user to read over long durations.
To learn more, visit the ClearType area of the Microsoft typography site.