A disco ball (also known as a mirror ball or glitter ball) is a roughly spherical object that reflects light directed at it in many directions, producing a complex display. Its surface consists of hundreds or thousands of facets, nearly all of approximately the same shape and size, and each has a mirrored surface. Usually, it is mounted well above the heads of the people present, suspended from a device that causes it to rotate steadily on a vertical axis, and illuminated by spotlights, so that stationary viewers experience beams of light flashing over them, and see myriad spots of light spinning around the walls of the room.
Miniature glitter balls are sold as novelties and used for several decorative purposes, including dangling from the rear-view mirror of an automobile or Christmas tree ornaments. Glitter balls may have inspired a homemade version of the sparkleball, the American outsider craft of building decorative light balls out of Christmas lights and plastic cups.
