Dust your window frames, especially the tops of sashes and window sills, every time you clean. Twice a year (or as needed), clean the trim with warm soapy water and let it air dry. In regards to mildew, spray a mixture of vinegar and water directly on the mold, and let the mixture sit. Wipe and let it dry. Then clean it with soapy water. If your window trim develops water spots (window sills are especially prone to this as water can collect on the shelf), clean them with distilled water or spray on rubbing alcohol and wipe them down. In damp rooms such as basements and bathrooms, use a dehumidifier or open the windows to allow air to circulate.
A sash window or hung sash window is made of one or more movable panels, or “sashes”, that form a frame to hold panes of glass, which are often separated from other panes (or “lights”) by glazing bars, also known as muntins. A window sill is the bottom piece of trim, or the ledge at the bottom of the window