In most cases, a duvet cover is constructed by stitching together two rectangular sheets of cloth on all four sides. One sheet is then cut lengthwise along the center, allowing the duvet to be fitted within the cover once it has been folded. Additionally, high-end duvet covers include ties at each corner, which allow the duvet cover to be fastened to the duvet at each of the four spots where it is tied. This design prevents the duvet from being bunched up within the cover.