Country dancing is designed for social mixing, primarily so
that eligible young males and females meet and assess each other. Although we
know of many examples of ceremonial dances, seasonal dances and occupational
dances, there is no definite example of country dancing before the 15th century.
Certainly there are tunes from 1300 onwards which are suggestive but they are
without evidence of social context.
A convenient starting point would be the paintings of Pieter Brueghel (early 1500s) and the end point would be the first world war. Social dancing obviously continued after 1918 but it evolved into ballroom dancing at the formal end of the social scale, or solo performance at the informal end. When you no longer touch a member of the opposite sex, it hardly qualifies as country dancing!
The main forms of country dancing are: circle dancing, longways set, square set and couple dancing. The couple dance first appears in Bavaria in the late 18th century and rapidly spreads around Europe. The most famous couple dances are also the names of time-signatures: waltz and polka. Circle dancing is known from classical times but doesn't become a mixed sex dance until the 15th century. In 16th century England it was still possible to distinguish between aristocratic courtly dancing (little or no touching) and peasant dancing. By the time of John Playford's "English Dancing Master (1651) it was a dance for everyone. The English term "Country Dance" was adopted all across Europe, and became corrupted into "Contredance" in many languages. Even in modern America the phrase "Contra Dance" is used alongside the more familiar term "square dance" or "barn dance".
The Longways set was the most popular type of country dance in the first edition of Playford's book. A line of males faced a line of females "for as many as will". "The Grand old Duke of York" is the most familiar example of this kind of dance. By the 1820s it was considered old-fashioned.
The square set, or quadrille was a group of 8 people, a couple along each side. "The Roger de Coverley" and the "Eightsome Reel" are among the most famous examples of this kind of dance. This still survives in Ireland, under the name "set dancing" or "figure dancing".
The bagpipe was the best instrument for outdoor dancing because of its loudness. Every European country, not just Scotland, used their own local variant of the bagpipe for country dancing. From the late 17th century fiddles began to take over, and dancing moved indoors. The main impetus for the development of the concertina, the melodeon and the accordian in the nineteenth century was to satisfy the market for a loud instrument for country dancing. Jane Austen, Charles Dickens and Thomas Hardy all loved country dancing and put detailed desciptions into their novels.
Some country dances are confined to their place of origin: Strathspeys in Scotland, Mazurkas in Hungary. The appeal of country dancing is almost completely confined to Christian countries. Having said that, klezmer tunes (originally Jewish) are now cropping up in public dances. The Scottish gaelic word ceilidh (Irish ceili) is sometimes used to mean country dancing, though the original meaning was a gathering for singing and dancing. Most country dancing is pretty robust in style but in Scotland, from the late nineteenth century, a very smooth and ornate style was cultivated. Soft shoes are worn. This makes Scottish country dancing very close to ballroom dancing, particularly since formal dress (white dresses and genuine kilts) are often de rigeur. Appalachian dancers go to the opposite extreme, with metal caps fitted to the shoes. Couple dances with a highly developed element of display, such as the tango, do not qualify as country dances.
The stage show "Riverdance" was a shot in the arm for Irish country dancing. The appeal was partly due to the emphasis on solo displays rather than couple dances. Ireland, like many other countries, has promoted country dancing in state schools, but this has generally been in decline on the school curriculum since the 1940s.
Many types of dance notation exist but none are widely used. Instead dancers follow a caller or an MC (Master of Ceremonies) who shouts out changes in the figures.