Saanich International Folkdancers Association

The term folk dance describes dances that share some or all of the following attributes:

• they are dances performed at social functions by people with little or no professional training, often to traditional music, or music based on traditional music;
• they are not designed for public performance or the stage, although traditional folk dances may be later arranged and set for stage performances;
• their execution is dominated by an inherited tradition rather than by innovation (although like all folk traditions, they do evolve).
• new dancers often learn informally, by observing others and/or receiving help from others.

More controversially, some people define folk dancing as dancing for which there is no governing body or dancing for which there are no competitive or professional performances.

Reference: http://en.wikipedia.org/wiki/Folk_dancing