Scottish Country Dancing (SCD) is a modern form of the “country dancing” popular in England and Scotland in the 18th century.
In 1923, the Scottish Country Dance Society (SCDS, later “Royal” Scottish Country Dance Society or RSCDS) was founded with the aim of collecting and preserving the old country dances and standardising the descriptions and footwork. This standardisation has certainly done a lot to make SCD into something that can be enjoyed internationally. In fact, Scottish Country Dancing is probably more alive today than it ever was in the past, and this is to a very large extent due to the efforts of the RSCDS.
SCD is a very social form of dancing, and you get to dance with a group of people at once instead of just with one partner. It involves groups of six to ten people (normally), in mixed sex ‘sets’, dancing to reels, jigs or strathspeys. The dance often combines solo figures for the “first couple” in the set with the other dancers in the ‘set’ joining in at various points. You interact with the others in the ‘set’. There are classes, workshops, balls and social dances being held in places all over the world. It is nice to be able to travel and join a SCD group for a night nearly everywhere you go.
Think of SCD as a cross between square or contra dance (although there is no caller) and ballet; there are about a dozen basic formations which will get you through quite a number of dances, although many dances have their own quirks and specialities which make them unique, and fun to dance. There is also more emphasis on “steps” than in, say, ceilidh dancing, but the basic technique can be learned by attending local classes which run during the winter months in Scotland.
Even though there are so many dances, you don't have to learn all of them by heart. The programmes for balls and social evenings are usually published well before the event, so everybody can obtain crib sheets and learn the dances from them in advance. Videos of a large number of dances are now available on the web and are linked to the main Dance Databases. Also, at the event itself dances are frequently recapped nowadays or even sometimes walked through slowly before the music starts.