In my option, irssi is the best irc-client ever created. It is lightweight, well customizable and stable. With screen you can keep your irssi online 24/7, and then you can connect to your client from any machine that has Internet connection. My best uptime with irssi is about 60 days, so it is pretty stable. (Reboot killed my irssi)

But here is list why irssi is the best irc-client:

• Fast and lightweight - works on almost any machine
• Console application (no gui) - you can ssh to it and irc without X-server running
• No mouse - I simply love this, I don’t have to move my hands away from the keyboard!
• Customizable - Almost everything can be changed. And there is also nice perl scripting support. (look at script directory)
• Logging - Good logging that even supports log-rotation
• Themes - Lots of cool themes.
• Proxy - You can load irssi-proxy module and connect to your irssi with any irc-client. I think that this is also the best proxy software.

For me it is essential application. I simply can’t live without it.

Irssi homepage