A game of snooker (called a frame) starts with 21 balls on the table, not including the white cue ball. “You’ve got your cue ball, and your main goal is to get an object ball in the pocket. Consider the most simple case: a cue ball moving in a straight line, and striking the object ball perfectly square on. However, it’s pretty rare for a cue ball, object ball and pocket to be perfectly aligned, so most snooker shots involve the cue ball striking the object ball at an angle. A cue ball carrying topspin will follow the object ball after the collision, while sufficient backspin will cause the cue ball to screw backwards, moving in the opposite direction to the object ball.