Definition of NetBIOS over TCP/IP (NetBT) in Network Encyclopedia.
What is NetBIOS over TCP/IP (NetBT)?
NetBT is the NetBIOS session-layer protocol and application programming interfaces (APIs) running on top of the TCP/IP network protocol. NetBIOS over TCP/IP (NetBT) supports NetBIOS session and naming functions such as the discovery, resolution, and release of NetBIOS names on a TCP/IP network, which allows the NetBIOS interface and client/server protocol to be extended over wide area networks (WANs).

This can be done effectively only if you manage name processes such as NetBIOS name registration centrally using the Windows Internet Name Service (WINS) on Microsoft Windows NT.
Broadcast-based name registrations usually don’t work over an internetwork because routers are typically configured not to forward broadcast packets to remote subnets.
The Server, Workstation, NetLogon, Browser, and Messenger services on Windows NT interact with NetBT by using the Transport Driver Interface (TDI) networking component.