PostScript Type 1 (with double-byte support). Adobe PostScript fonts launched the desktop publishing industry and are used today by publishers, corporations, and government agencies for high-quality output to laser printers, imagesetters, and platesetters. Each PostScript font requires two files, one for the screen and one for use by the printer’s RIP (raster image processor). Mac OS X is the only operating system that provides native PostScript Type 1 font support.
OpenType. OpenType fonts (extension .otf) can contain 65,000 different glyphs, so type can be set in non-Roman languages such as Japanese, Chinese, and Korean. There are Macintosh- and Windows-specific OpenType formats; Mac OS X supports both. Font format developed by Adobe and Microsoft; combines aspects of PostScript and TrueType font formats; fully scalable, meaning the font can be resized without losing quality.
TrueType. TrueType fonts (extension .ttf) are typically used in home and office environments. A single file contains both screen and printer font information. Font file format created by Apple, but used on both Macintosh and Windows platforms; can be resized to any size without losing quality; also looks the same when printed as it does on the screen. The TrueType font is the most common font format used by both Mac OS X and Windows platforms.