A wound involves the breaking or cutting of the interior layer of skin (called the dermis). Breaking only the outer layer of skin (epidermis) is not sufficient (R v Smith (1837) 8 Carrington and Payne 173). A wound does not need to be caused by a weapon, such as a knife, and can include something as minor as a split lip (R v Shepherd [2003] NSWCCA 351).