Curtains & drapes can have multiple functions. First, they can be used in the same manner as shades and blinds, but can be used in conjunction with them in a more decorative fashion. A common window treatment is to have a pull-down blind for firm control of light and visibility, but to also have a sheer drape that will admit light, with a heavier drape over that. The heavy drape often has insulative qualities to keep heat in or out. Other decorative elements might be fringing on the drapes, curtain pulls and valances to finish the top.