A French door, which is also sometimes referred to as a French window, is a door made up of panes or panels of glass. Frames or partitions separate each pane. Glass panes are generally rectangular in shape and make up the majority of the surface of the door. This type of door is typically used as a style element. It is frequently used as a way to bring more natural light into a home, or as a way to divide rooms and set them apart while still maintaining an open feel to the overall space.
While functional, they are typically used more for aesthetic purposes, to create a dramatic effect. For example, a great use of this style element is to make indoor and outdoor living spaces feel connected. A French door-style opening from the kitchen onto the patio area ties the two spaces together. A pair of French doors opening onto the balcony from the master bedroom brings the outdoors inside.
Because a French door is so versatile, it may be a repeating theme in a home. A pair, or in some cases, many pairs of doors are often used to keep an open feel.