Nappy rash, also known as diaper rash, is a common condition that affects infants and young children. It is characterised by red, inflamed skin in the diaper area, including the buttocks, genital area, and folds of the thighs. Nappy rash occurs when the skin in the diaper area becomes irritated and inflamed due to prolonged exposure to urine and feces, as well as friction and moisture trapped inside the diaper.