A nod of the head, a wry smile and they are off, fiddles hopping, feet stomping and the gravelly voices belting out the tunes. Music seems to run in the blood of the Irish and once you set foot in the Old Sod, it seems you are never more than a stone's throw from a session.
For all but the most ardent disciples, it is the lively atmosphere that matters as much as the music - the friendly banter, wild stories and back-slapping good cheer of a pub session are like nothing else on the planet.
Even suggesting a top 10 list of venues is enough to start an argument but here are our some of our favourites for the best craic agus ceol (fun and music) in the country.
1. Fleadh Cheoil na hÉireann, changing venues
Held in late August, the Fleadh is the mother of all Irish music festivals and attracts about 250,000 people over eight fun-filled days. You will have to qualify to enter the music, singing, dancing and whistling competitions but really, they are only part of the story. It is the impromptu evening sessions, rowdy sing-a-longs, concerts and céilís (traditional dances) that really draw the crowds.
2. Hughes, Dublin
You will find trad music session in pubs all over Dublin, from the manufactured craic in Temple Bar to the folksy tunes in ever-popular O'Donoghues, but if you want to see some serious musicians head for Hughes (19 Chancery St, 01-872-6540) near the law courts. Expect a decent pint, excellent sessions, set-dancing and shaggy-bearded locals with misty eyes.
3. The Crane Bar, Galway
The music at the brightly-coloured Crane is just as it should be: no egos, no pretension, just addictive, toe-tapping rhythms and a heartfelt love of the craft. Few pubs have space to dance but the atmospheric old Crane is an exception and is the best place in Galway to catch a céilí in full swing.
4. C. Ní Cairbre, Drogheda
Browning walls plastered with newspaper clippings and dog-eared postcards greet you at this unashamedly modest pub. Owned by the same family since 1880, C. Ní Cairbre (Carberrys) is as authentic as it gets. It is the kind of timeless place where musicians just turn up and start to play. On Wednesdays, sean nós (old style) singers gather to set the room aglow.
5. Willie Clancy Summer School, County Clare
Some of the best musicians in the world gather in Miltown Malbay for Ireland's largest traditional music school. In addition to expert workshops , there are lectures, recitals, céilís and exhibitions at the eight-day event. Day and night the pubs are jammed and music comes from every direction as informal sessions pop up in the town's bars and spill out onto the streets and into people's homes.
6. De Barra Folk Club, Clonakilty
Flutes, fiddles, bodhráns, pipes and mandolins cover the walls at this temple of traditional music in County Cork. De Barra's, with its vibrant but easy-going attitude, offers intimate gigs in the sitting room, a purpose-built auditorium and a long list of big-name regulars.
7. MacDiarmada's, Doolin
Tucked away in the wilds of west Clare is a one horse town with three great music pubs. Lots of musicians live in this uniquely rocky area and MacDiarmada's is the locals' favourite. If it is standing room only head for nearby McGann's or O'Connor's, though there is no guarantee of a seat there either.
8. An Spailpín Fánach, Cork
Sitting just across the road from the Beamish brewery, you are guaranteed a decent pint at the old-world Spailpín Fánach or the Wandering Labourer (28 South Main St , 021-427-7949). Much loved by locals for its laid-back sessions, open fires and snug corners, it is the place to quietly nurse a pint, join the craic or just nod in the corner and let the melody waft over you.
9. Tí Joe Watty's, Kilronan
Take a trip to Tí Joe Watty's on Inis Móir, the largest of the Aran Islands, and you are almost guaranteed a jig. This is one of the island's oldest and most traditional pubs, with trad sessions every night in summer and a mellow atmosphere that lets the tourists shake a leg. Purists might object to the come-al-ye attitude but there is no arguing with the music.
10. Leos Tavern, Crolly, Donegal
The enigmatic, undulating rhythms of Enya and Clannad wooed the world in the 1980s and Tábhairne Leo is where their sound was born. Set between the Atlantic Ocean and the rugged peak of Mount Errigal, it is a place for legendary sessions and glitters with the gold and platinum discs of Leo's famous children.
For more information on traditional Irish music and culture, festivals, events and gigs visit www.comhaltas.ie.
Etain O'Carroll is a co-author of Lonely Planet's latest Ireland guide.
The article 'Top 10 places to hear traditional Irish music' was published in partnership with Lonely Planet.