A shoe is an item of footwear evolved at first to protect the human foot and later, additionally, as an item of decoration in itself. The foot contains more bones than any other single part of the body, and has evolved over hundreds of thousands of years in relation to vastly varied terrain and climatic conditions. Together with the proprioceptive system, it is what makes balance and ambulation possible.
Until recent years, shoes were not worn by most of the world's population—largely because they could not afford them. Only with the advent of mass production, making available for the first time the cheap flip-flop-type sandal, for example, has shoe-wearing become predominant.
The design of shoes has varied enormously through time, and from culture to culture, with appearance originally being tied to function. Additionally fashion has often dictated whether shoes have, for example, very high heels or no heels at all. Contemporary footwear varies in style, complexity and cost, from the most basic sandal, via high fashion shoes for women sometimes costing thousands of dollars a pair, to complex boots specially designed for mountaineering or skiing. Shoes have traditionally been made from leather, wood or canvas, but are increasingly made from rubber, plastics, and other petrochemical-derived materials.