French doors first appeared in France, which is how they got their name. These patio doors typically feature glass panes for most of their length and can have stylish grilles. Because of this abundance of light, they are sometimes also called French windows even though they are considered a type of patio door. There are two types of French doors - hinged and sliding.
Hinged French Doors
Hinged French doors break down into categories - single-hinged and double-hinged. A single-hinged French door is a single panel that is hinged on the side and swings open and closed.
Double-hinged French doors have two panels, or doors, that part in the middle and swing open and closed. In most designs, both panels, or doors, will swing open and closed. But, there are some designs where one panel is fixed so only one panel swings open and closed.
Sliding French Doors
Sliding French doors consist of four panels and slide open and closed instead of swinging. They are categorized as four-panel or multi-slide patio doors. With four-panel French doors, three panels are operable and can slide while a fourth panel is fixed and inoperable.
With multi-slide French doors, each of the four panels is operable and can slide open and closed. Depending on the type of installation, multi-slide doors will either disappear into the wall or stack together on an end of the track.