A kippah , yarmulke, yamaka, bullcap, or koppel is a brimless cap, usually made of cloth, traditionally worn by Jewish males to fulfill the customary requirement that the head be covered. It is worn by all men in Orthodox Jewish communities during prayers and by most Orthodox Jewish men at all other times. Among non-Orthodox Jewish communities, some who wear them do so at all times, while others wear them only during prayer, while attending a synagogue, or in other ceremonies.