Curtain, in interior design, ornamental fabric generally hangs to regulate the admission of light at windows and help drafts from door or window openings. curtains, generally of a heavy material, arranged to fall straight in cosmetic crowds are also called curtains. portieres are heavy curtains hung in doorways. the significance of using curtains as home and event scenery. curtains allow you to help dust from coming into your room. when windows and doors are open, dust patches enter your home with the wind you can.