tl;dr use a web interface or install a Firefox extension.
The BRL-CAD community operates in the #brlcad channel on the Freenode IRC network (irc.freenode.net:6667). The channel serves as a real-time avenue for interacting with other BRL-CAD users and developers around the world. This document explains IRC, chatting, and, and recommended software.
 What is IRC?
IRC stands for Internet Relay Chat. It's a method of communication where you join a channel to read and write messages to other people in that channel. It's similar to instant messaging but for chatting with lots of people simultaneously.
 What is Chatting?
Chatting is real-time text-based communication. It's a means to interact and collaborate with other people that may be on the other side of the world.
 Why Chat?
- Fun: while the focus of the channel is to talk about BRL-CAD, everyone is there voluntarily. It's a friendly gathering for people with a common interest.
- Persistence: IRC has many special features that make it really easy and convenient to stay interactively engaged in a community. There are services for registering identities and keeping discussions under control. You can leave messages for others even if you don't know their e-mail or phone number. You can keep searchable transcripts of discussions. You can get involved in discussions that span minutes, days, or more.
- One to Many: you're talking with a group of people instantly. While some people will idly lurk in a channel to only read discussions, you have the opportunity to interact with many core project participants including developers to get answers to questions, leverage the insights of others, and contribute back to BRL-CAD.
- Commit Notification: changes to BRL-CAD's source code and changes to the website are announced in real-time to the IRC channel so you can see modifications being made to BRL-CAD as they happen.
 IRC Etiquette
If this is your first time using IRC, there are a few things you should know and expect:
- Be polite. Everyone is there voluntarily and not necessarily to help you. Be nice or leave.
- Be patient. If you have a question, ask your question and wait. People are on the channel from time zones around the world so your question might be read immediately or several hours later. It's considered rude to ask a question and then leave within a few minutes.
- Be considerate. When you connect to a channel, wait a few minutes to get a feel for any discussions already under way. You do not need to announce or introduce yourself, but should be mindful to stay on topic. Don't waste other people's time.
- Ask smart questions. Don't ask to ask ("Can I ask a question?"). Don't ask if someone is there ("Is John here?"). Ask the real question you intended to ask them and wait patiently for a response. See How to Ask Questions the Smart Way for more suggestions.
 What Software?
Depending on your operating system, there are lots of choices available. A comprehensive selection of clients can be found in this IRC client list.
For the lazy, you could use a web interface or install a Firefox extension.
This document was based in-part on the LinuxChix IRC for Beginners guide. Thanks ladies!