What is "sean-nós"?
"Sean-nós" (pronounced "shan-nos") literally means "old style." It refers to the Irish language songs, poetry, and dances that were popular during the 17th and 18th centuries. Although songs and steps are passed down from teacher to student and between artists, each performance is unique and personal to the performer.
Sean-nós singing is one of the finest of the traditional Irish arts. It is often characterized by unaccompanied free rhythm, relative lack of vibrato or dynamic change, and (sometimes) by the use of rapid ornamentation. "Sean-nós" singing is usually performed in Gaeilge (the Irish language); the same type of singing performed in English is frequently referred to as "traditional" singing instead. There are also a number of traditional songs that are referred to as "macaronic" -- part of the song is in English and part of the song is in Gaeilge.
Different regions in Ireland each have their own unique style of sean-nós singing. Singers from the west (Connemara) and south (Munster) of Ireland tend to sing in a highly ornamented style, as where singers from the north (Ulster, especially County Donegal) usually stick more closely to the original melody. The one uniting characteristic of sean-nós singers regardless of region is their emphasis on the story behind the song.
Some videos of sean-nós singing:
SNNW 2015 Instructor Brían ÓhAirt singing at 2010 Irish Music Awards:
SNNW 2014 Instructor Máirín Uí Chéide as featured on TG4:
SNNW 2010 Instructor Lillis Ó Laoire:
Sean-nós dancing is quite different in many ways from the "step dancing" or "Riverdance" that many Americans are familiar with. There are no fancy costumes, no stiff upper body, and no memorizing routines here! Instead, sean-nós dancing features a very relaxed upper body and arms, steps kept low to the ground, and dancers improvising steps to match the music. Unlike step dancing (where the dancer is the focus), sean-nós dancers are part of the music, providing percussion with their feet. Each dancer has their own style and steps, which they will combine in their own unique way to each song -- no two performances are alike!
Some videos of sean-nós dancing:
Footage from 2010 Sean-nós NW Festival (featuring Kevin Burke on fiddle):
Footage from 2014 Sean-nós NW Festival (featuring vocals by Máirín Uí Chéide)
Other clips of amazing sean-nós dancers:
https://youtu.be/gWSkVhssyS0 (Devane brothers)
https://youtu.be/PhtqGih57jA (Aidan Vaughn)
https://youtu.be/ZXZl4DPCqtw (Edwina Guckian)