what is a duvet cover?
Duvet and cover. A duvet is essentially a soft flat bag filled with down, feathers or a synthetic alternative. It is recommended that duvets are inserted into a removable cover, much like a pillow and pillow case. Duvets and duvet covers are designed to be used alone (with no sheets) because the insert can be removed and the outer bag can be laundered, but many people use them with sheets anyway.