A socket is a logical entity which identifies a network endpoint. A scocket is identified by 3 parameters, ie the IP address, port as well as stream socket ( TCP ) or datagram socket ( UDP ).
Port a unique number whih tries to identify the application process for example FTP port no 21 means FTP server listens on port 21. If a server listens on port no 21 on a machine then no other applications can listen on this port for the same transport.
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