The UNIX OS was born in the late 1960s. AT&T Bell Labs released an operating system called Unix written in C, which allows quicker modification, acceptance, and portability.
It began as a one-man project under the leadership of Ken Thompson of Bell Labs. It went on to become most widely used operating systems. Unix is a proprietary operating system.
The Unix OS works on CLI (Command Line Interface), but recently, there have been developments for GUI on Unix systems. Unix is an OS which is popular in companies, universities big enterprises, etc.