Characteristics of Type on the Web
Although the basic rules of typography are much the same for both web pages and conventional print documents, type on-screen and type printed on paper are different in crucial ways. The computer screen renders typefaces at a much lower resolution than is found in books, magazines, and even pages output from inexpensive printers. Most magazine and book typography is printed at 1200 dots per inch (dpi) or greater, whereas computer screens rarely show more than about 85 pixels per inch (ppi).
The current Apple Macintosh and Microsoft Windows operating systems use anti-aliased type to increase the apparent resolution of type on the computer screen. Anti-aliasing works by smoothing the edges around type, so that at normal screen reading distances the type looks much like high-resolution printed type. Anti-aliasing works: careful legibility and reading studies have long shown that it improves reading speed and accuracy. The letterforms look fuzzy when enlarged but appear sharp when viewed under normal reading conditions (fig. 8.1).