A bank shot in billiards involves driving an object ball off one or more rails before it enters the pocket. This shot is critical when a direct path to a pocket is blocked, or as a strategic move for cue ball control. The fundamental principle governing bank shots is the angle of incidence equals the angle of reflection – meaning, the angle at which the ball hits the rail will be approximately the same angle at which it leaves the rail. However, real-world factors like cue ball speed, spin (english), and the condition of the rails (cushions) can subtly alter this reflection angle. Players often employ aiming systems, like using the table's diamonds, or mental visualization to identify the precise spot on the rail where the object ball needs to make contact. Mastering bank shots requires consistent practice to develop a sensitive feel for how these variables interact, allowing you to accurately judge the necessary speed and spin to guide the object ball to its intended destination.