A duvet cover is a fabric casing that covers a comforter. If you have an expensive feather or down comforter, a duvet cover protects the comforter from wear and tear, and prevents it from becoming soiled. The comforter will move around inside the duvet cover if it is not secured. Ties are used to hold the comforter in place and keep it from moving around during use.
Turn the duvet cover inside out. Place the comforter over the duvet cover, with the corners of the comforter aligned with the corners of the duvet cover.
Locate the ties on the corners of the duvet cover. Pull a tie at the bottom corner of the duvet cover over the corresponding corner of the comforter; tie it in a tight knot. Repeat this with the other bottom tie.
Turn the duvet cover right-side out. Pull the comforter up inside the duvet cover and adjust it if needed.
Tie the top corner ties in the duvet cover to the top corners of the comforter. Button or zip the duvet cover to close it.