Last night I decided I was going to go dancing. My husband, daughter, sisters and their husbands and nieces went out to a nice place where a lot of people go. We got to the place we were going dancing. There was a guy at the door checking ID's to make sure there wasn't anyone under the age of 21 going in. Of course we were all over 21 so there weren't any issues. We all went in and found us a table. We then decided to order some drinks and about that time a waitress came over and asked us what we would like to have. We all gave her our order and she went to get the drinks. While she was away a good song started playing and we all decided to dance. We all went out on the dance floor and danced until the end of the song. We went back to our table and our drinks arrived as soon as we got back. We all drank our drink and decided to dance some more. We stayed for a few hours and danced. We all then decided it was time to go home. We all went to the door. We told one another bye and we all left and went home. 
Question: Why did people dance together?
They are friends.