NetBIOS
Short for Network Basic Input/Output System, NetBIOS was developed by IBM, Microsoft, and Sytek. This is what allows software applications, commonly used on IBM compatible computers to communicate with network hardware, and allow data to be transmitted properly over a network.
NetBIOS commonly communicates on ports 137, 138 and 139. If your network or computer has a firewall setup that blocks any of these ports it is likely warning messages will be received when your computer communicates with another computer that utilizes NetBIOS (for example: Microsoft Windows). To prevent these errors or warnings you must provide access on these ports.
Also see: NetBEUI, Network definitions, Port
