Sheets are large pieces of fabric used to cover beds. They come in various materials, such as cotton, linen, and polyester, and are available in different sizes to fit mattresses. Sheets typically include a flat sheet that lies on top and a fitted sheet that wraps around the mattress. In addition to bed sheets, the term "sheets" can also refer to paper used for writing or printing. These sheets are often available in standard sizes, such as A4 or letter size, and can be used for various purposes, including note-taking, printing documents, or creating art.