What is the function of the eight ball in pool?

It is the most popular game of pool. All 15 balls are racked w/ the 8 ball in the middle. After the rack is broken, the opposing players take stripes or solids after a ball is pocketed.Once all of a person's balls are pocketed the eight ball must be correctly pocketed to win the game. This game is also know as stripes and solids.