A bed sheet is a rectangular piece of cloth used either singly or in a pair as bedding, which is larger in length and width than a mattress, and which is placed immediately above a mattress or bed, but below blankets and other bedding (such as comforters and bedspreads). A bottom sheet is laid above the mattress, and may be either a flat sheet or a fitted sheet (a sheet which has been sewn with elastic or a drawstring along the hem of the top, sides and bottom of the sheet to prevent it from slipping off of the mattress). A top sheet, in the many countries where they are used, is a flat sheet, which is placed above a bottom sheet and below other bedding.
Sateen:Sateen is another common weave style, using a three or four yarn over, one yarn under weave. This means the fabric is usually thicker and more tightly woven than percale — often with a higher thread count, too. Sateen is known for its lustrous sheen, soft and smooth feel, and beautiful drape. It also tends to be warmer than percale, due to being thicker.