Window shutters are rigid panels set on vertically aligned hinges at the edges of window openings, which can be folded in over the windows to block light or increase privacy. Shutters are similar in function to outdoor window screens, but are more decorative. They are often painted in colors which complement or add variety to the facade color, as shutters are often a highly visible part of a building's exterior.

The rigid panels turn on hinges at the window edges. Their ability to fold over the opening distinguishes them from purely decorative fixed panels.

Outdoor window screens perform a similar covering function but use the different roller or jalousie arrangement described there.