A “session” is an informal gathering of musicians who meet to play traditional music. Sessions are mainly associated with Ireland but can be found all over the world. Players of traditional music will usually be able to find a session wherever they go and they are a great way of making friends in a new town, go and introduce yourself. They are a fantastic way to build your playing confidence, hear new tunes and have a great time.
The melodies people play at sessions are usually the more common tunes, after attending a few you will start to recognize tunes that get played every time (sometimes more than once). The best way to decide which tunes to learn is listening to what everyone joins in on and asking someone what a particular tune is called. Different sessions have different tunes that are common to them but not necessarily commonly known/played in sessions elsewhere.
Most sessions work by someone starting a set of tunes, usually each tune is played three times through before the person leading the set changes to the next tune. The person leading might give some kind of signal they are about to change to a new tune, but most players will momentarily stop playing after three times through to listen to the next tune before joining back in if they know it. Some sessions will have a “leader” who starts most of the sets, in some sessions players take it in turns to start sets, and sometimes you just have to jump in and start playing when there is a momentary lull. You will most likely try and avoid leading a set until you have gained some confidence on your instrument and have built up a good size repertoire of tunes. Don’t start a tune unless you are sure there are others there who know the tune and will join in and back you up, there’s nothing worse than starting off a tune and no one joins in (everyone is listening to you play).