In the sport of cricket, ball tampering is an action in which a fielder illegally alters the condition of the ball. The primary motivation of ball tampering is to interfere with the aerodynamics of the ball to aid swing bowling.
Definition : Under Law 41, subsection 3 of the Laws of Cricket, the ball may be polished without the use of an artificial substance, may be dried with a towel if it is wet, and have mud removed from it under supervision; all other actions which alter the condition of the ball are illegal. These are usually taken to include rubbing the ball on the ground, scuffing with a fingernail or other sharp object, or tampering with the seam of the ball