Each font is stored as one or more files on your hard drive, usually in the Fonts folder of your Windows directory. You can find them by opening the Fonts folder, or by clicking the Start Button, then choosing Settings, Control Panel and Fonts. Windows fonts usually have one of two extensions. The extention TTF identifies a TrueType Font, which can be scaled to any size by your word processor or other programs. Files with the extension FON are bitmapped fonts - they're designed to be displayed in one size only.
Some fonts require four separate files - for normal, italic, bold and bold italic faces.
Although there's no specific limit on the number of fonts you can install, the operating system generally chokes when it has to manage more than 1,000. The exact limit depends on the name of each font and its location on your hard drive, which sounds weird but is true. Unfortunately, system performance can degrade before you reach half the theoretical limit. The simplest way to figure out which fonts you want is to browse the Fonts directory and double-click file names you don't recognize. A window will pop up with the typeface in various sizes.