"PC" is an initialism for "personal computer". The IBM Personal Computer incorporated the designation in its model name. It is sometimes useful to distinguish personal computers of the "IBM Personal Computer" family from personal computers made by other manufacturers. For example, "PC" is used in contrast with "Mac", an Apple Macintosh computer.[5][6][7][8] . Since none of these Apple products were mainframes or time-sharing systems, they were all "personal computers" and not "PC" (brand) computers.