The tooth fairy is a popular American legend where children place a lost tooth under their pillow at night and receive a gift in exchange from the tooth fairy. This tradition exists universally across cultures but takes different forms, such as in Spanish speaking countries where he is known as "Ratoncito Pérez". The tooth fairy was introduced to children's mythology through a story written in 1894 by a Jesuit in Spain at the request of a young king who had lost a tooth.