Hook grip is a specific grip method used by Weightlifters and powerlifters for lifts such as the snatch, clean, and deadlift.
Hook grip is when you wrap your thumb around the barbell first, then your fingers go around your thumb.
The hook grip creates a lock on the barbell so that there isn’t a direction the bar can roll out of your hand, similar to a mixed grip (overhand and underhand).
Not only will it build a more symmetrical grip strength from side to side but it will also have a better skill transfer to your Olympic lifts if you were to use it in your deadlifts.
With a more secure grip on the bar using a hook grip, this also allows your upper arms to stay more relaxed and the force generated from your legs will better transfer to the barbell.
Although it’s very uncomfortable at first, the hook grip can be a very beneficial tool to have in your “gym bag”.