A "Flat Sheet" is a large piece of fabric, typically rectangular, used in bedding. It is designed to cover the mattress and provide a comfortable layer between the sleeper and the blanket or comforter. Flat sheets are commonly made from materials like cotton, polyester, or linen, and they come in various sizes to fit different mattresses, such as twin, full, queen, and king. Flat sheets can also serve decorative purposes, adding color and style to a bedroom. They are often used in conjunction with fitted sheets, which have elastic corners to hold them in place on the mattress. Many people choose to use flat sheets for easy washing and versatility in bedding arrangements.