ELI5 what is an irc bouncer?
An irc bouncer is a middleman between you and an irc network. It connects to a network like a normal client and instead of connecting directly to an irc network you connect to it. Usually you would set it up to log for you and show you some or all of the messages it received while you were disconnected. In this way your nick is always present in your channels and you can see what was talked about while you were away.
source: https://www.reddit.com/r/irc/comments/35vcth/comment/cr86hcs...
I never understood why IRC servers don't just store history and let clients query for it. This seems like a small addition to the protocol that would have made it a lot more pleasant to use. You could always turn the feature off in your channel/server if you want ephemerality.