A diaper (also called a nappy in South Africa, Ireland, United Kingdom, New Zealand, Australia and Zimbabwe) is a type of underwear that allows one to defecate or urinate, without the use of a toilet. When diapers become soiled, they require changing, generally by a second person such as a parent or caregiver. Failure to change a diaper on a sufficiently regular basis can result in skin problems around the area covered by the diaper.