Bed Bath and Beyond suggests the purpose of a duvet cover is to protect the down comforter inside, which is usually pricey. Duvet covers also provide an easy, cheap way to redecorate by changing it often and without having to buy a new down piece.
Bed Bath and Beyond also recommends duvet covers because they are more easily stored than a regular comforter because it is only the shell, not the fuller down or feathers.
Duvet covers can be used alone in summer months, providing a lighter source of covering. In fall, use it with the down comforter. And in cold winter months, add another blanket.
Unlike the down comforter, duvet covers can be easily removed, and washed and dried at home. They protect the comforter from dust and dirt that needs to be removed but without the hassle of having to dry clean the down inside.
Duvet covers come in all fabrics, including easy-care cotton. Look for the cleaning tag attached to see the type of care recommended. Like sheets, duvet covers come in twin size, full, queen and king. Match the cover size to the sheet size.
Duvet covers are sold in the bedding department. Specialty bedding stores, department stores and discount stores usually carry a variety of choices.