OSX – An operating system (OS), in its most general sense, is software that allows a user to run other applications on a computing device. The operating system manages a computer’s software hardware resources, including:
Input devices such as a keyboard and mouse.
- Output devices such as display monitors, printers and scanners.
- Network devices such as modems, routers and network connections.
- Storage devices such as internal and external drives.
OS is suffixed by the version number of the operating system, (X) is used to indicate an unknown version number.
( Source: www.techopedia.com)