A bank shot is a shot in which the projectile bounces, ricochets or "banks" off a barrier before reaching its target.
In pool a bank shot bounces one or more rails before landing in a pocket. This technique is often used when a direct shot is difficult or impossible, due to bad angles or other balls being in the way. The incident speed of the ball can affect the angle at which it is reflected, due to the collision being somewhat inelastic.
In basketball a bank shot ricochets of the backboard to fall through the hoop. It usually doesn't require as much precision or control to sink a bank shot as it does a straight shot. As long as the ball hits the board in a fairly specific area with the appropriate angle, a slight variation in speed generally won't stop it from falling through. Factors to consider when banking a shot in basketball include the pressure inside the ball and the type of backboard - the ball will bounce harder of the rigid glass surfaces used in gymnasiums than it will off the springy, fiberglass boards used on outdoor courts.
In ice hockey, a shot puck will either bounce off a goalpost, another player, or the opposing goaltender and then cross the goal line for a bank shot.
In old cowboy movies you often see trick shooters banking gunshots. Don't do this. You might kill someone!