Type foundry or font foundry is a company or an individual that designs and distributes different typefaces. Originally, type foundries manufactured and sold metal and wood typefaces and matrices for line-casting machines like the Linotype and Monotype machines designed to be printed on letterpress printers.
Today’s digital type foundries accumulate and distribute typefaces (typically as digitized fonts) created by type designers, who may either be freelancers operating their own independent foundry, or employed by another foundry. Type foundries often provide custom type design services.
Type foundries can be placed into three main categories: corporate type foundries (for example Adobe, Apple), large form type foundries (Ascender Corporation, Font Bureau, Microsoft Typography), and independent type foundries (Comicraft, P22, Typotheque, and hundreds more).
There are hundreds if not thousands of foundries online where you can buy and download fonts. Many new ones are also constantly introduced, as typefaces is a growing industry with a constant demand.