IRC itself is a teleconferencing system, which (through the use of the client-server model) is well-suited to running on many machines in a distributed fashion. A typical setup involves a single process (the server) forming a central point for clients (or other servers) to connect to, performing the required message delivery/multiplexing and other functions.
IRC client programs connect over the Internet to
central IRC servers that distribute the messages around the network. The following
sections provide more information: