What is Unix?
Unix is a powerful, multi-user environment that has been implemented on a variety of platforms. Once the domain of servers and advanced users, it has become accessible to novices as well through the popularity of Linux and Mac OS X. With the notable exception of Microsoft Windows, all current major operating systems have some kind of Unix at their cores.
Unix was developed at Bell Labs in 1969, but in the past three decades many others have contributed to its evolution. In reality, Unix is not so much a single operating system as it is a standard upon which organizations and companies base their own systems.