A litter box (sometimes called a sand box, a litter tray or a litter pan) is a place for cats and some other pets to use as a toilet. Litter boxes usually need to be cleaned regularly. Cats, for example, wish to have their box cleaned every two to three days. Some cats create litterboxes in places like playgrounds and sandpits. Litterboxes usually produce bad smells, which can be avoided by special litter. Many people buy a special kind of clay to fill the box, for this reason.