Authentic casino chips are usually made from a clay composite, which gives them heft and makes that satisfying sound when they are clinked together or thrown down during a bet. Generally speaking, a 300-chip set will meet the needs of a 7-8 person game, and 500 chips are easily sufficient for 9-10 people.
Poker chips are used in lieu of cash during games for several reasons, they speed up the game and make it easy for the players to identify the bet amount and pot size.