A Collision Hull, also known as hitbox or collision model, is an invisible 3D model placed around an object in a video game. This model is used for collision detection and is sometimes referred to as a collision geometry file. The name "hitbox" is derived from older games, which used a simple cube. The hit box is the reason that when standing on the edge of a wall, your character will "float"; the hit box is still resting on the wall.