IRC is a vital part of participating in the Linux community, but choosing an IRC client can be a daunting task for new Linux users. If you're ready to start jumping into IRC, but not sure which client to start with, we've got five great clients to choose from.
Now, I know how attached some folks are to their IRC clients. IRC users tend to fall into two camps: casual users and power users. The casual users are people who dip into IRC on occasion to participate in a conversation or IRC meeting, but don't live in IRC. Then you've got the power users: folks who spend enormous chunks of time in IRC as part of their job and/or because they're part of a community that does most of its work in chat.
Linux users can choose from more IRC clients than you can shake a stick at, dozens of clients depending on how expansive your definition is. To winnow it down to a reasonable herd of clients, I decided to rule out a couple of clients that are undeniably awesome but not well-suited to many users. For instance, Emacs has several clients, but if you're not using Emacs then you're not going to want to learn it just to use a nifty IRC client.
Also, I wanted to focus more on clients that would appeal to newer Linux users getting started with IRC. So with that in mind, let's get started with Pidgin.
IRC and More: Pidgin
Pidgin is not an IRC client. Well, it's not exclusively an IRC client. Pidgin is actually a multi-protocol IM and IRC client that handles pretty much any instant messaging service you want to throw at it. And this is why Pidgin tops my personal list of clients.
For users who communicate with co-workers over IRC and IM, Pidgin is the best solution because it doesn't require maintaining two programs. Pidgin may not have quite as many IRC-specific features as some of the others, but it's a solid IRC client and is very user friendly. Pidgin gives you the ability to either integrate your IRC conversations in the same window as your conversations on IM networks or to separate out conversations into multiple windows.
Whatever your work habits, Pidgin should fit right in. Like to be notified right away when someone mentions your nick in chat? Pidgin can do anything from changing the system tray icon to giving an audio cue. With the right plugins, Pidgin can even correct some common spelling mistakes and expand abbreviations. That's true for all conversations in Pidgin as well, not just IRC.
If you're looking for an all-in-one application, start with Pidgin. It's available for most Linux distros, just look for the pidgin package. Some distros include it by default with GNOME (like openSUSE; others just keep it in the main repos.
Full Featured IRC: Konversation
Konversation is a solid and full-featured IRC client for KDE. Of course, it'll run on GNOME or under other window managers on Linux as well. Konversation is a dedicated IRC client, and it's one I recommend because it has all the features most users want, and it's easy to get started with.
With Konversation you get a simple tabbed interface that's highly configurable. You can set up notifications to your liking, including On Screen Display (OSD) notifications so that you'll get an overlay whenever someone says your nick in channel. This makes it easy to see if you need to go to the client and respond, or if it's just an offhand comment that you can safely ignore while you go about your work.
Konversation lets you bookmark your favorite channels, has some handy features for searching for text in a conversation, and makes it really easy to insert "special" characters in chat. Nice if you happen to need an accented character on the fly. I also like Konversation's "URL Catcher" to easily keep track of URLs pasted into conversations. While you can run clients like Irssi in a console (see below), Konversation lets you run a Konsole instance within the client for a little terminal emulator action in the IRC client. That's one way to conserve a little screen space.
I also like Konversation's Quick Buttons feature, which makes it dead simple to add a button for actions you use frequently in IRC. By default it comes with buttons for kicking users, using whois, parting channels, but you can add pretty much any IRC command you use frequently.
Konversation should be available for most major Linux distros as konversation. It has a fairly comprehensive help manual and shouldn't be hard at all to get started with.
Tried and True: XChat
Getting a bit more into the "advanced" category is XChat. Wait, don't be frightened! When I say advanced, it's not lingo for "hard to use." XChat is a friendly GUI IRC client that any user should be able to get around nicely. But there's a bit more under the hood than a welcoming GUI.
In addition to all the usual features you'd want from an IRC client, XChat has plenty of scripts and plugins to extend its functionality. Yes, Konversation and Pidgin have plugins and scripts, but XChat has a really extensive collection of scripts that will let you do all manner of fun stuff. Everything from scripts to insert entries from RSS feeds to full-on scripts to allow you to play Chess over IRC. You can also plug in scripts to ignore private conversation attempts, control MP3 players via XChat and more.
XChat's interface is straightforward and easy to use, but it can also be customized quite a bit. Want a transparent chat window, or to make an image your chat background? No problem. You can choose between a tabbed or tree interface for managing your separate rooms while in IRC. XChat even lets you view the raw IRC log as it goes by, if you're into that sort of thing.
Another reason I like to recommend XChat is that it's available for Linux and Windows. This makes it a nice client for users who have to use Windows at work but prefer Linux on their personal computers. The XChat folks have a short starter guide for new users, as well as a forum for anyone looking for help (or to provide it!). Though the guide uses Windows screenshots, it's applicable to the Linux version as well.
You'll find XChat for pretty much every major Linux distro, and the XChat site has links to Windows downloads if you need them.
Browser Based IRC: Chatzilla
Maybe you don't want to install a full-blown application for IRC. Spend most of your time in Firefox? Check out the ChatZilla add-on for Firefox. It brings IRC right to your browser, just like the olden days when chat was part of the Netscape Suite.
You might think that a browser-based IRC client would be stripped down, but ChatZilla is remarkably full-featured. It has an easy to use interface, allows you to create your own command aliases, and generally has all the features most folks need to participate in IRC day to day. ChatZilla even supports plugins, though the collection of plugins for ChatZilla isn't nearly as extensive as collection of scripts available for XChat or Irssi.
Another reason I like ChatZilla? Like XChat, it's multi-platform. It'll work on Linux, Windows, and Mac OS X. So if you're on more than one OS, ChatZilla is a good way to keep a consistent IRC program. Note that if you want to get the full effect of the old-style Netscape suite, you can go for SeaMonkey, which rolls up the browser, mail client, IRC, and HTML editing all in one application.
If you're not running SeaMonkey, you can grab ChatZilla just like any other Firefox extension. The easiest way is to go to the Tools menu and select Add-ons, then in the Get Add-ons tab, search for "ChatZilla" and install the extension. Note that you'll see several add-ons that provide language packs for ChatZilla, so be sure to grab the plain ChatZilla extension unless you also want one of the localized versions.
Going Old School IRC: Irssi
If you want to go old school, then Irssi is the client for you. Unlike all the other IRC clients I've mentioned so far, Irssi is a CLI-based client. Why would you want something CLI-based? A couple of reasons.
First, you might want to keep your client running full-time using GNU Screen. By running Irssi inside a screen session, you can connect from multiple locations and never miss a word. This is such a popular use case with Irssi that they have a handy guide to using the two in tandem.
Irssi also sports a bunch of scripts that let you do everything from display battery status in your Irssi Statusbar to logging URLs and pushing them to delicious. If you're spending an enormous amount of time in IRC, you might find some (or many) of the scripts useful. Whether you want to be notified of new mail in your IRC window or query Google or IRC straight from Irssi, you can find dozens of pre-written scripts for the client. And, of course, if you know a bit of Perl and want to extend Irssi you can do that too.
Even though Irssi is CLI-based, that doesn't mean you can't have nice things. There are quite a few themes for Irssi to spruce up the interface. The interface may be sparse, but it's not lacking for features. Irssi can do multiple windows, split screens, and generally just about anything you'd want to do that you can do in GUI clients. It will take a bit longer to learn, but if you're going to be spending a lot of time in IRC, Irssi might be worth learning.
Want to give Irssi a go? Check the documentation after installing the irssi package. There's a decent amount of good documentation and it'll help get you started and on your way to chatting up a storm.
All of the IRC clients I've listed here are worthy apps. Since they're all open source, feel free to install and test them all out if you don't already have a preference. Over the years I've used them all and always keep my eyes peeled for new and exciting ones like Quassel. I'd also love to hear your favorites, so give a shout in the comments for your favorite IRC clients and look for me on Freenode as jzb.