The history of Unix dates back to the mid-1960s when the Massachusetts Institute of Technology, AT&T Bell Labs, and General Electric were developing an experimental time sharing operating system called Multics for the GE-645 mainfra Multics introduced many innovations, but had many problems. Bell Labs, frustrated by the size and complexity of Multics but not the aims, slowly pulled out of the project. Their last researchers to leave Multics, Ken Thompson, Dennis Ritchie, M. D. McIlroy, and J. F. Ossanna, decided to redo the work on a much smaller scale.
In 1970, Peter Neumann coined the project name UNICS (UNiplexed Information and Computing Service) as a pun on Multics (Multiplexed Information and Computer Services): the new operating system was an emasculated Multics.
In 1972, Unix was rewritten in the C programming language. The migration from assembly to the higher-level language C, resulted in much more portable software, requiring only a relatively small amount of machine-dependent code to be replaced when porting Unix to other computing platforms. Bell Labs produced several versions of Unix that are collectively referred to as Research Unix. In 1975, the first source license for UNIX was sold to faculty at the University of Illinois Department of Computer Science. UIUC Graduate Student Greg Chesson (who had worked on the UNIX kernel at Bell Labs) was instrumental in negotiating the terms of this license.
During the late 1970s and early 1980s, the influence of Unix in academic circles led to large-scale adoption of Unix (BSD and System V) by commercial startups, some of the most notable of which are Sequent, HP-UX, Solaris, AIX, and Xenix. In the late 1980s, System V Release 4 (SVR4) was developed by AT&T Unix System Laboratories and Sun Microsystems. SVR4 was subsequently adopted by many commercial Unix vendors.
In the 1990s, Unix-like systems grew in popularity as Linux and BSD distributions were developed through collaboration by a worldwide network of programmers. Later, Apple also released Darwin, which became the core of the OS X operating system.