Irish Stepdancing
Stepdancing as a modern form is descended directly from Sean-Nós stepdancing. There are several different forms of stepdancing in Ireland (such as the Connemara style stepdancing), but the style most familiar is the Munster, or southern, form, which has been formalised by An Coimisiún le Rincí Gaelacha.
Irish stepdancing is primarily done in competitions, public performances or other formal settings and falls into two broad categories based on the shoes worn: hard shoe and soft shoe dances.
Soft shoe dances include the reel, slip jig, light jig, and single jig. Reels are in 2/4 or 4/4 time. Slip jigs are in 9/8 time. Light and single jigs are in 6/8 time, with different emphasis within the measure distinguishing the music. Hard shoe dances include the hornpipe, in 2/4 time, the treble jig, in a slow 6/8, the treble reel, and traditional sets, which are a group of 36 dances with set music and steps. Many traditional sets have irregular musical phrasing. There are also more advanced "non-traditional sets" done by advanced dancers. These have set music, but not steps.
Irish Social Dancing
Irish social, or céilí (pronounced "kay-lee"), dances vary widely throughout Ireland and the rest of the world. A céilí dance may be performed with as few as three people and as many as sixteen. Céilí dances may also be danced with an unlimited number of couples in a Céilí line or proceeding around in a circle (Such as in the "Walls of Limerick" or "Bonfire Dance"). These dances are often fast-paced and may be quite complicated. In a social setting, a céilí dance may be "called" -- that is, the upcoming steps are announced during the dance for the benefit of newcomers.
The term céilí dance was invented in the late 19th century by the Gaelic League, to distinguish non-quadrille dances from the quadrille-based set dances, which were thought to be a British or foreign influence in Ireland.
There is a distinction between the noun céilí, and the adjective. A céilí is a social gathering featuring Irish music and dance. Céilí dancing is a specific type of Irish dance. Some céilithe (the plural of céilí) will only have céilí dancing, some will only have set dancing, and some will be mixed.
Set Dances
Set dances are folk dances of Ireland based on French quadrilles. Most are done in square sets of four couples and consist of several "figures" each of which has a number of parts. Throughout the dance, as they perform the figures, the dancers use various steps, with the style of the step varying from place to place and from set to set. The sets themselves come from various parts of Ireland are often named for their place of origin, such as the Corofin Plain Set or the Clare Lancers Set. The music used can be reels, jigs, slides or polkas, but only one type of tune is used for a given figure although types are frequently mixed within any given set.
Irish set dancing is popular throughout Ireland as well as in Canada, the United States, Australia, Europe and other countries. Social set dancing is not usually competitive, but there are competitions held by Comhaltas Ceoltóirí Éireann (Gathering of Musicians of Ireland, pronounced "KOHL-tas KYOHL-TOE-ree AY-ren"). The term "traditional set dancing" is also used to describe a different type of competitive solo stepdancing taught by Irish dance schools.