Many of them have specialized uses, and are not commonly known to micro-computer users. Some, however we should know about, since with the importance of the Internet, we will often be in communication with systems other than the one on our own machine. It is used principally in file servers on networks and by some home users who want more than Windows 95 can deliver. It is also used in networks as a file server. UNIX and many of its variants are used in university settings where it can ,due to the nature if its license, be adapted for study and development.
Commercial versions are also widely used as network servers, and industrial control machines.
Many people believe that Apple's Mac computer does not have an operating system, since it is all sold as a single piece of equipment. This is far from the truth. The organization for a Mac is the same as for any other computer. Finally another word about drivers. You may purchase a new hardware component for your computer, and find that you also get one or two floppy disks with it.