socket
The program's end of a network conversation: an address plus a port.
A socket is an operating-system endpoint for network I/O, identified by IP address, port and protocol; a TCP connection is a pair of sockets.
Examples
The sensor's end of its broker connection is the socket 192.168.1.37 port 49152, TCP; the broker's end is 192.168.1.10 port 1883.
Two sensors can both reach port 1883 on the laptop without mixing traffic, because each connection is a different pair of sockets.
See also