A ballroom is a large room inside a building, the designated puprose of which is holding dances (balls).
Ballrooms are generally quite large, and may have ceilings higher than other rooms in the same building. The large amount of space for dancing, as well as the highly formal tone of events have given rise to ballroom dancing.
Ballroom dance is a style of partner dance which originated in the western world and is now enjoyed both socially and competitively around the globe.
Most competitive ballroom dances were social and/or folk dances before being formalized as ballroom dances, and many of these dances are still danced as social and folk dance.
Some ballroom dance instructors specialize in the dances of one place or time, or in fad dances, short-lived, time-specific dances which may be associated with the music or style of an era ("The Twist") or a particular song ("YMCA", "La Macarena").