is conceptually an end point for communication, and the
API is the defacto cross platform standard API used to create, configure,
read from, write to, and otherwise manage sockets.
A socket is identified using the IP address
of the network node, and the port number
within the network node.
If a network node wants to send UDP data
onto the network it first creates
a socket, then sends the data to that socket. If a network node wants to
receive UDP data it first creates a socket on an address that is known
by the node that will send the data, then reads the data from that socket.
If a network node wants to send TCP data
onto the network it first
creates a socket, connects that socket to a socket on a remote node,
then sends the data to that socket. If a network node wants to receive
TCP data it first creates a socket, then listens on that socket for
incoming connections. When a connection is received it may (optionally)
create a new socket to handle the connection and then receive the data
on the new socket – leaving the original socket listening for additional
It can be seen then that any one network node can be involved in multiple
network conversations simultaneously – with a socket being used at each
end of each unique conversation.
Sockets can also be used to send and receive broadcast and multicast
communications – which are both a form of one to many communications.