Topic summary
Dance crews

Extracted from the Wikipedia article History of hip-hop dance.
Dance crews
A dance crew is a team of street dancers who come together to develop new moves and battle other crews. As hip-hop culture spread throughout New York City, the more often breaking crews got together to battle against each other. It was during this time that the different dance moves within breaking developed organically. All styles of hip-hop are rooted in battling, and being a part of a crew was the only way to learn when these styles began because they were not taught in studios: they all started out as social dances. Forming and participating in a crew is how street dancers practiced, improved, made friends, and built relationships. In breaking in particular, battling is how b-boys/b-girls improved their skill.