IRC = Internet Relay Chat. You've heard of those infamous "chat rooms" you can find on the internet? Most are quite disgusting, but a few can be interesting.
Advantage of a chat room is that several people can gather in one place and make comments in real time, though one line at a time... sort of like an internet "party line."
Chat can be fun, but what's on the net is pretty bad, so I wrote my own chat server a couple of years ago - password protected to keep the riff-raff out.