A flat sheet, also known as a top sheet, is a rectangular piece of fabric that lies between the sleeper and the blanket or comforter. Typically made from soft, breathable materials such as cotton, flat sheets add an extra layer of comfort and help protect blankets or duvets from dirt and body. They are usually hemmed on all sides, with one end often featuring a wider hem or decorative trim for aesthetic appeal. Flat sheets can be used alone in warmer climates or as part of a full bedding set in cooler weather. They are easy to fold, wash, and tuck in, offering both practical and hygienic benefits for bedding.