As for the implied question, "what are sockets", you might find RFC 147 and port numbers to be of some value.

Coming from a networking background (as opposed to a programming background), I'd describe a socket as the combination of both an IP address and a port number, used to uniquely identify a specific network application for remote connections.   This applies to both client and server applications.

Anymonk what can articulate it better/more_clearly, please expand on or correct my hipshoot description.
  cheers,
  ybiC
  striving toward Perl Adept
  (it's pronounced "why-bick")