Bed sheet

A bed sheet is a large rectangular piece of cotton or linen cloth bed cover. It is this sheet that one typically lies on. They were traditionally white, but now often various patterns are used. They supposed to be larger than the bed, so they be tucked under the mattress in order to be kept in place. A "fitted" bed sheet is not a simple flat cloth but is sewn to match the shape of the mattress. The corners includes elastic so as to stay tucked under the mattress. Sometimes confused with a "comforter" it is usually found underneath a comforter but over the matress cover.

In fiction, bed sheets are often knotted by prisoners in order to be used as a rope and escape by climbing down the window.