Rotation, sometimes called rotation pool or 61, is a pool game, played with a pocketed billiards table, cue ball, and triangular rack of fifteen billiard balls, in which the lowest-numbered object ball on the table must be always struck by the cue ball first, to attempt to pocket numbered balls for points. Some attractions of rotation include performing unconventional or difficult shots to reach the correct ball, and quite often making risky attempts to score higher numbers of points by performing advanced shots such as combination shots, bank shots, and swerves.