A diaper /ˈdaɪpə(r)/ or a nappy is a type of underwear that allows the wearer to urinate or defecate without using a toilet, by absorbing or containing waste products to prevent soiling of outer clothing or the external environment. When diapers become wet or 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.
