NetBIOS stands for Network Basic Input/Output System, which is a networking industry standard that allows applications on different computers to communicate with each other across a local area network (LAN) . It is an API (Application Programming Interface) that operates at the session layer (Layer 5) of the OSI (Open Systems Interconnection) model, providing various services such as name service, datagram service, and session service to facilitate communication between devices on a network.

NetBIOS was created in 1983 by Sytek Inc. for software communication over IBM PC Network LAN technology. It was originally designed to standardize and free applications from having to understand the details of the network, including error recovery in session mode. NetBIOS has been used in Ethernet and Token Ring networks and is included as part of the NetBIOS Extended User Interface (NetBEUI) .

NetBIOS is not a network protocol, but rather a network service that enables applications on separate computers to communicate over a local area network. It has been used with various network protocols, including IEEE 802.2 and IPX/SPX using the NetBIOS Frames (NBF) and NetBIOS over IPX/SPX (NBX) protocols, respectively. In modern networks, NetBIOS normally runs over TCP/IP via the NetBIOS over TCP/IP (NBT) protocol.

NetBIOS provides a set of services that enable devices to communicate and exchange data, including name resolution, connectionless communication via datagrams, and connection-oriented communication via sessions. NetBIOS machines periodically broadcast their names over the network so that Network Neighborhood or My Network Places can catalog them.

In conclusion, NetBIOS is a legacy networking protocol that was widely used in the past for communication and resource sharing within local area networks (LANs) . It provides a standardized way for applications on computers to communicate with each other over a LAN.