In the roaring 20s there was a new birth on American entertainment. The music changed, the acting and stage plays changed and most importantly dance changed. Dance became more than backup for an artist or a band or a solo performance by a very well known dancer, it became it's own shows and productions. Choreographers incorporated storylines, plots and characters in dance shows, making them more lengthy and full of substance. Currently, there are movies that incorporate dance in their plots that continues the idea of choreographers from the 1920s.

The three purposes of dance are Recreational, Ceremonial, and Artistic Expression.

Recreational dance is for fun. The dances you see and do at parties, in the club, in your bedroom when you think no one is looking, are all recreational.

Ceremonial dance is for special events. Dance used to be used for the coming of visitors to the land, weddings, funerals, and celebrations in other cultures. In America we seldomly see any ceremonial dancing. It is arguably said that dancing in parades, and on certain award shows, qualifies as ceremonial dancing because those are events that celebrate people and events.

The definition of Artistic Expression is the "human effort to immitate, suppliment or counteract the work of nature." Any dance that you see that displays a deep emotion or gives a certain message.

A dance can have more than one purpose.

http://www.thefreedictionary.com/Artistic+expression

There isn't any ancient artifacts to trace back when dance started or why dance became part of human culture. There are only stories of traditions that tribes and clans have practiced over the years. Africa seems to be the place where all types of dance evolves from.

 "The only way to preserve dance movements from generation to generation was by demonstration, imitation, practice and personal supervision" History of Dance ( Wikipedia, 2012)