Short for network operating system, NOS is the software that allows multiple computers to communicate, share files and hardware devices with one another. Earlier versions of Microsoft Windows and Apple operating systems were not designed for single computer usage and not network usage. As computer networks started to emerge and be used more frequently, network operating systems began to be developed.
The first network operating system was Novell NetWare, released in 1983. After Netware, other network operating systems were released, including Banyan VINES and Microsoft Windows NT. Some examples of other network operating systems include Windows 2000, Microsoft Windows XP, Sun Solaris, and Linux.