A network operating system is a supervisory software program that resides on the server. It controls how the network operates by defining who can use the network and how information and peripherals are shared among users.

Novell Netware

• most popular
• good solution of a PC and Mac network

Microsoft Windows NT

• getting popular
• good solution of PC networks
• easier to set up than Novell Netware
  

AppleShare

• Macintosh only
• does not scale to fit a large network
  

UNIX/NFS