Mattress comforter or a continental quilt (or simply quilt) or duvet in British English, is a type of bedding made of two lengths fabric or covering sewn together and filled with insulative materials for warmth, traditionally down or feathers, wool or cotton batting, silk, or polyester and other down alternative fibers.
It's typically better at regulating temperature than manmade fill.
Naturally insulating without being heavy.
Protect it with a duvet cover which keeps it clean and increases its life.
Air it outside a few hours twice a year to maintain freshness.
To clean it, follow the manufacturer's instructions & clean it in a year before storing it for the season.