IRC

IRC /I-R-C/ n.  [Internet Relay Chat] A worldwide "party
   line" network that allows one to converse with others in real
   time.  IRC is structured as a network of Internet servers, each of
   which accepts connections from client programs, one per user.  The
   IRC community and the {Usenet} and {MUD} communities overlap
   to some extent, including both hackers and regular folks who have
   discovered the wonders of computer networks.  Some Usenet jargon
   has been adopted on IRC, as have some conventions such as
   {emoticon}s.  There is also a vigorous native jargon,
   represented in this lexicon by entries marked `[IRC]'.  See also
   {talk mode}.