Quassel IRC is a modern, cross-platform, distributed IRC client
based on the Qt framework.

Distributed means that one (or multiple) client(s) can attach to
and detach from a central core that stays permanently online --
much like the popular combination of screen and a text-based IRC
client such as WeeChat, and similar to (but much more featureful
than) so-called BNCs.  Re-attaching your client will show your IRC
session in the same state as you left it in (plus whatever happened
while you were gone), and this even when you re-attach from a
different location.

In addition, Quassel IRC can be used like a traditional client,
with providing both client and core functionality in one binary.
This so-called "Monolithic Client" completely hides the distributed
nature, so for a purely local installation, Quassel IRC can be
setup very easily.