The simple definition of s a movable seat, with a back, for a single person gives no indication of the truly vast range of objects that qualify under this description. Furthermore, few people today are aware of the fact that for much of its history and chairs go back through classical times to the time of the pharaohs the chair was reserved for kings, lords, and bishops; ordinary folk sat on backless chests, benches, or stools.
The word chair derives from the Latin cathedra, hence the designation of a church that was the seat of a bishop as a cathedral. Medieval chairs, religious or secular, were large framed affairs often with linenfold panels, and frequently provided with a canopy or tester, typically placed on a dais to further emphasize the importance of the occupant.
During the 18th century, before furniture production passed largely into the hands of factories, chairs were made with more curves than before, a process that required considerable material, since curved sections typically legs and backs were usually sawn out of the solid. The progress from straight and sometimes turned legs to shapes such as the cabriole and the klismos, and the development of designs not requiring stretchers, but relying instead on techniques such as knee blocks, corner blocks, and wider tenons in substantial rails, can be followed as a logical timeline up to the point where commercial pressures for continual innovation resulted in the riot of revival styles that characterizes the 19th century.
Reference: http://www.finewoodworking.com/PlansAndProjects/PlansAndProjectsAllAbout.aspx?id=3042
