Character encoding is a table in a font or a computer operating system that maps character codes to glyphs in a font. Most operating systems today represent character codes with an 8-bit unit of data known as a byte. Thus, character encoding tables today are restricted to at most 256 character codes. Not all operating system manufacturers use the same character encoding. For example, the Macintosh platform uses the standard Macintosh character set as defined by Apple Computer, Inc., while the Windows operating system uses another encoding entirely, as defined by Microsoft. Fortunately, OpenType fonts (and standard Type 1 fonts) contain all the glyphs needed for both these encodings, so they work correctly not only with these two systems, but others as well. Not all operating system manufacturers use the same character encoding. For example, the Macintosh platform uses the standard Macintosh character set as defined by Apple Computer, Inc., while the Windows operating system uses another encoding entirely, as defined by Microsoft. Fortunately, standard Type 1 fonts contain all the glyphs needed for both these encodings, so they work correctly not only with these two systems, but others as well. Also see character, glyph, keyboard layout.