Irish traditional music sessions are mostly informal gatherings at which people play Irish traditional music. The Irish language word for "session" is seisiún. Generally sessions feature the playing of tunes, although songs, dance and story telling is often included.
The general session scheme is that someone starts a tune, and those who know it join in. Good session etiquette requires not playing if one does not know the tune, and waiting until a tune one knows comes along. In an "open" session, anyone who is able to play Irish music is welcome.
Most often there are more-or-less recognized session leaders; sometimes there are no leaders. At times a song will be sung or a slow air played by a single musician between sets.
Session at the Old Dubliner
The objective in a session is not to provide music for an audience of passive listeners; although any non-playing attendees are welcome and often come for the express purpose of listening, the music is most of all for the musicians themselves. The session is an experience that is shared, not a performance that is bought and sold. Session audience etiquette is to remain silent during the playing, not to request specific tunes, and applaud discretely.
The sessions are a key aspect of traditional music; some say it is the main sphere in which the music is formulated and innovated. Further, the sessions enable less advanced musicians to practice in a group. Socially, sessions have often been compared to an evening of playing card games, where the conversation and camaraderie are an essential component. In many rural communities in Ireland, sessions are an integral part of community life.
Typically, the first tune is followed by another two or three tunes in a set. The art of putting together a set is hard to put into words, but the tunes must flow from one to another in terms of key and melodic structure, without being so similar as to all sound the same. The tunes of a set will usually all be of the same sort, i.e. all jigs or all reels, although on rare occasions and amongst a more skilled group of players a complementary tune of a different sort will be included, such as a slip jig amongst the jigs. Although bands sometimes arrange sets of reels and jigs together, this is uncommon in an Irish session context. After the set ends, someone will usually start another.
Additionally, at events such as NTIF, new or original tunes may be exchanged. This is common where musicians from different countries come together.