UNIX is a powerful computer operating system originally developed at AT&T Bell Laboratories. It is used in various scientific, engineering, and academic communities because it provides multi-user and multi-tasking environment, flexibility, portability, email and networking capabilities. It also provides numerous programming, text processing and scientific utilities.

It also plays a vital role in government and business sector. Over the years, two major forms of UNIX (with several vendor’s variants of each) have evolved: The AT&T UNIX System V and the Berkeley Software Distribution (BSD).