Unix is a family of operating systems that are all derived from the original AT&T Unix developed at Bell Labs in 1969. Unix is a multitasking, multiuser operating system that is characterized by the implementation of many small modular software tools that can be combined using a scripting language known as the Unix shell. Unix and Unix-like operating systems are currently used widely on servers, workstations, and mobile devices.

Originally developed for internal use at Bell Labs in the late 1970s, AT&T licensed Unix to a variety of outside parties, leading to a number of academic and commercial Unix variants. These include:


In 1991, Linus Torvalds released the open source Linux kernel as a Unix-like free alternative to proprietary Unix systems. It had since exploded into dozens, if not hundreds of different variant distributions.

In 1992, a free derivative of BSD Unix was released, leading to the NetBSD and FreeBSD projects. Since 1994 BSD Unix has developed several different branches, including OpenBSD.

In 2000, Apple released a BSD Unix System named Darwin that eventually became the core of the macOS operating system.


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