Note: Many topics at this site are reduced versions of the text in "The Encyclopedia of Networking and Telecommunications." Search results will not be as extensive as a search of the book's CD-ROM.

The NetBIOS (Network Basic Input Output System) was designed by IBM and Sytek to support client/server computing in LAN environments. NetBEUI (NetBIOS Extended User Interface) is a NetBIOS support protocol. According to the paper at the dtool Web site (see link on the related entries page), NetBEUI formalized the transport layer frame that was never standardized in NetBIOS. It specifies how NetBIOS applications send and receive messages over the NetBIOS frame protocol. NetBEUI talks directly to NDIS in the MAC layer, bypassing any internetworking functions, and so is not a routable protocol. IBM used NetBEUI in its LAN Manager Server and Microsoft later adopted it as a LAN networking protocol.

Both NetBIOS and NetBEUI were widely implemented in various versions of Microsoft Windows, although Microsoft now pushes TCP/IP as the network protocol of choice. NetBIOS and NetBEUI are still included in Windows products and some network administrators may find them useful in the small LAN environment. Since you cannot build internetworks with NetBEUI, most organizations have moved to NetBIOS and Windows Sockets over TCP/IP.