A folding camera is a camera type. Folding cameras fold into a compact and rugged package for storage.
The lens and shutter are attached to a 
lens-board which is connected to the body of the camera by a light-tight folding bellows.
When the camera is fully unfolded it provides the correct focus distance from the film.
The key advantage of folding cameras is their excellent physical-size to film-size ratio when the camera is folded for storage.