A bed sheet is a rectangular piece of cloth that is used as bedding, either alone or in pairs, and is put directly below or above the bed occupants. In the many nations where they are utilized, a top sheet is a flat sheet that lies directly beneath the bed occupants. Above the mattress, a bottom sheet is spread, and the bed occupants lie on it. A fitted sheet is one that has been sewed to form a wide pocket around the top, sides, and bottom edge of a mattress, with elastic or a drawstring in the hem to prevent it from slipping off the bottom of the mattress. Over the top sheet, blankets, quilts, duvets, comforters, and other bed covers are placed.