UNIX is an operating system (OS) that AT&T's Bell Labs first introduced in 1969. Since then many competitors have emerged in the marketplace, including derivatives, such as the various flavors of Linux. Nevertheless, UNIX remains an important aspect of study at most network administration colleges, and the reason for this is the many advantages that the OS still provides in the real world and in academic environments.
Security
The architects developed UNIX from the ground up in a very secure way. The account system and user verification mechanism are part of the UNIX foundation. What this means is that UNIX defends against most exploitations at a very basic level, and programs lack the privilege to undermine that approach.
Full Multitasking and Protected Memory
One of the greatest advantages UNIX provides is the capability to run multiple programs for multiple distinct users without those instances interfering with each other or the overall operation of the OS. UNIX is a true multitasking environment with full support for multiple users and instances.
Virtual Memory
The approach to virtual memory used by UNIX remains one of the most efficient strategies to achieve this goal. Although some believed that access to greater amounts of memory and greater memory affordability would eventually diminish this advantage, that hasn't been the case. In fact, modern memory-hungry applications have been able to make even better use of the UNIX virtual memory system.
Toolbox
UNIX includes a rich set of utilities and commands. The emphasis here is on isolating the core purpose of a feature. Even if UNIX were not still so widely popular, would likely still teach it in order to use this compartmentalization at a teaching platform for fundamental concepts.
Customization
The true power of the small app approach used by UNIX is that the user can string these apps together in an unlimited fashion. In other words, UNIX users are able to generate individualized user experiences in a much easier and more efficient manner than most other platforms allow for. UNIX also has a very lean kernel, which means that users can actually tailor the OS to their specific needs, hence Linux.
Unified File System
Another powerful and fundamental advantage of UNIX is the unified file system. In UNIX, everything is a file, and that includes data, programs, including specific instances, and even actual devices, such as disk drives and printers. These files exist within a nested tree of files, regardless of how many physical devices are present, and that allows the user a very unique and precise control over the system.
Compatibility
Lastly, UNIX is a highly compatible and portable OS, and it arguably remains the most truly portable computing platform. After all, it can be fashioned to run on almost any hardware, and most modern portable devices are using a platform that is inevitably derived from UNIX. Another advantage of the small kernel mentioned earlier is that it can remain small, which makes it suitable to environments that lack a lot of memory, storage space and processing power.