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.