Terminology
The term "folk dance" is sometimes applied to dances of historical importance in European culture and history; typically originated before 20th century. For other cultures the terms "ethnic dance" or "traditional dance" are sometimes used, although the latter terms may encompass ceremonial dances.
There are a number of modern dances, such as hip hop dance, that evolve spontaneously, but the term "folk dance" is generally not applied to them, and the terms "street dance" or "vernacular dance" are used instead. The term "folk dance" is reserved for dances which are to a significant degree bound by tradition and originated in the times when the distinction existed between the dances of "common folk" and the dances of the "high society".
A number of modern ballroom dances originated from folk ones.
The terms "ethnic" and "traditional" are used when it is required to emphasize the cultural roots of the dance. In this sense, nearly all folk dances are ethnic ones. If some dances, such as polka, cross ethnic boundaries and even cross the boundary between "folk" and "ballroom dance", ethnic differences are often considerable enough to mention, e.g., Czech polka vs. German polka.
Not all ethnic dances are folk dances; for example, ritual dances or dances of ritual origin are not considered to be folk dances. Ritual dances are usually called "Religious dances" because of their purpose.
Read more about this topic: Folk Dances