An IRC FAQ (frequently-asked questions file) is included with many popular IRC programs when you download them. If you haven't yet downloaded IRC software, here's an FAQ to get you started.
What is IRC?
IRC stands for "Internet Relay Chat." It was originally written by Jarkko Oikarinen in 1988. Since starting in Finland, it has been used in over 60 countries around the world. It was designed as a replacement for the "talk" program, but has become much more than that. IRC is a multi-user chat system, where people convene on "channels" (a virtual place, usually with a topic of conversation) to talk in groups, or privately. IRC is constantly evolving, so the way things to work one week may not be the way they work the next. Read the MOTD (message of the day) every time you use IRC to keep up on any new happenings or server updates.
IRC gained international fame during the 1991 Persian Gulf War, where updates from around the world came across the wire, and most irc users who were online at the time gathered on a single channel to hear these reports. IRC had similar uses during the coup against Boris Yeltsin in September 1993, where IRC users from Moscow were giving live reports about the unstable situation there.
How is IRC set up?
The user runs a "client" program which connects to the IRC network via another program called a "server". Servers exist to pass messages from user to user over the IRC network.
What are good channels to try while using IRC?
#hottub and #initgame are almost always teeming with people. #hottub is meant to simulate a hot tub, and #initgame is a non-stop game of "inits" (initials). Join and try it.
What if someone tells me to type something cryptic?
Never type anything anyone tells you to without knowing what it is. There is a problem with typing certain commands with some clients that give anyone immediate control of your client (and thus can gain access to your account).
Where can I learn more?
You can find a longer version of this and similar FAQs (periodically updated) at C|Net's Shareware.com.
Where can I download free IRC software?
Here are some places to try. If these links are broken, do your own search.
Which IRC software do you use? Which do you think is best?
I use mIRC because it's mind-numbingly simple, which suits my simple and numb mind. People often tell me during chats that pIRCh is much more flexible and powerful. But I note that those people have to set up "scripts" and "events" and such, and frankly there's more to my life than online chatting. I keep it simple. To sum up: mIRC for all the most basic IRC stuff, and pIRCh for serious chatters.