NetBIOS (Network Basic Input/Output System) is a legacy networking protocol that allows applications on different devices within a local network to communicate. It provides services for name resolution, session management, and data transfer, enabling devices to be identified using human-readable names instead of IP addresses. NetBIOS operates over TCP/IP (NetBIOS over TCP/IP or NBT) using ports 137 (name service), 138 (datagram service), and 139 (session service). While commonly used in Windows networks for file sharing and printer discovery, NetBIOS has largely been replaced by modern protocols like DNS and Active Directory, though it still exists for backward compatibility. Due to security vulnerabilities, disabling NetBIOS is often recommended in enterprise environments unless explicitly required. Learn more: https://en.wikipedia.org/wiki/NetBios