The screen tool is most commonly used with irc clients. What it actually does is makes the program run in the background and then resume later. For this example im going to use the irssi irc client. First you need to start a term and type the following:
screen -S irc
Now the -S means what to call the actual session name. Now we have a session started, now lets launch irssi:
Now we see the normal screen and this is nothing new. Now press ctrl-a-d. Now your session has now gone away. Now say you want to come back later on another ssh session? well this is possible!:
screen -r irc
This now shows the session of irssi. Now isn't that COOL :). This is useful for all programs as well not just irc.