A duvet , usually called a comforter or quilt in American English, and a doona in Australian English, is a type of bedding consisting of a soft flat bag filled with either down, feathers, wool, cotton, silk, or a synthetic alternative, and is typically protected with a removable cover, analogous to a pillow and pillow case. The term duvet is mainly British, especially in reference to the bedding; rarely used in US English, it often refers to the cover. Sleepers often use a duvet without a top bed sheet, as the duvet cover can readily be removed and laundered as often as the bottom sheet.