The Cylinder in basketball is the area directly below the basket. It is where basket interference or goaltending occurs.
The Cylinder is an imaginary three-dimensional space that extends vertically from the rim of the basket.
Each player on the court has an invisible cylinder surrounding their body. The size of the cylinder varies based on the player's height and build. A player's cylinder is defined by the front, back, and sides of their torso.
Defensively, a player must stay within their cylinder and not invade an opponent's cylinder.
On offense, a player can't spread their arms or legs outside their cylinder to gain extra space. The Cylinder Rule helps referees determine who is at fault when contact occurs between two players. It ensures that players have enough room to make normal basketball moves.