A folk dance is a dance that has some or all of the following:
They are dances at social functions by people with little or no professional training. They are often to traditional music or music based on traditional music.
They are not made for public performance or the stage. Traditional folkdances may be later arranged and set for stage performances.
The way they are done is strongly about inherited tradition rather than making changes. Although like all folk traditions they do change over time.
New dancers often learn informally by watching others and/or getting help from others.
Even though some people argue with it, folk dancing can be dancing for with no governing body or dancing for which there are no competitive or professional performances.