OS X as an operating system family - discussion

OS X (originally Mac OS X) is a series of Unix-based graphical interface operating systems (OS) developed and marketed by Apple Inc. It is designed to run on Macintosh computers, having been pre-installed on all Macs since 2002. OS X is the fourth most popular general purpose OS; within the market of desktop, laptop and home computers, and by web usage, OS X is the second most widely used desktop OS after Windows. More: en.wikipedia.org.