TrueType fonts are the major scalable font format designed by Apple. The TTF rendering engine can be found on many platforms including Apple's OSX, Microsoft's Windows, Linux, and inside of printers.
TrueType is a scalable font developed by Apple Computer in the late 1980s. It supports both kerning and pixel-level hinting. It has supplanted Adobe's PostScript Type 1 fonts. The format itself is comprised of a series of tables containing information about the character outlines, spacing, kerning, hinting, and composing.