What does a defensive specialist do in volleyball?

Answer 1

Their name says it all. They specialize in defense. Usually what a D.S. will do is sub in for a person who plays front row, like an outside hitter serve and play till the rotation goes back to the front row. The difference between a d.s. and a libero is mainly that they can serve and the count as substitute while a libero can't serve (in club volleyball they can't) and they are a free sub.