A pocket shot in basketball refers to a shot that is taken from the pocket of the elbow or the pocket of someone's shot. A pocket shot is often used when someone does not have enough time to completely extend their arms into a full shot. It is also used by some players who prefer to shoot from the pocket of their shot. Players can feel this is a more comfortable position in some cases.
The advantage of a pocket shot is that you are able to release the ball quicker or feel more comfortable shooting. Shooting the ball quicker can be an advantage because it gives your defender less of a chance to reach you before you shoot. Being comfortable is one of the most important aspects of shooting and if players are more comfortable they are usually more successful.
A player with a consistent pocket shot is very rare in basketball. This is because there are very few players that prefer the comfort of a pocket shot over a normal jump shot. However, pocket shots are thrown up multiple times throughout in a game when a player is under duress and must shoot the ball quickly.