The basic anatomy of a shoe is recognizable, regardless of the specific style of footwear.
All shoes have a sole, which is the bottom of a shoe, in contact with the ground. Soles can be made from a variety of materials, although most modern shoes have soles made from natural rubber, polyurethane, or polyvinyl chloride (PVC) compounds.[53] Soles can be simple—a single material in a single layer—or they can be complex, with multiple structures or layers and materials. When various layers are used, soles may consist of an insole, midsole, and an outsole.[54]
The insole is the interior bottom of a shoe, which sits directly beneath the foot under the footbed (also known as sock liner). The purpose of the insole is to attach to the lasting margin of the upper, which is wrapped around the last during the closing of the shoe during the lasting operation. Insoles are usually made of cellulosic paper board or synthetic non woven insole board. Many shoes have removable and replaceable footbeds. Extra cushioning is often added for comfort (to control the shape, moisture, or smell of the shoe) or health reasons (to help deal with differences in the natural shape of the foot or positioning of the foot during standing or walking).[54]
The outsole is the layer in direct contact with the ground. Dress shoes often have leather or resin rubber outsoles; casual or work-oriented shoes have outsoles made of natural rubber or a synthetic material like polyurethane. The outsole may comprise a single piece or may be an assembly of separate pieces, often of different materials. On some shoes, the heel of the sole has a rubber plate for durability and traction, while the front is leather for style. Specialized shoes will often have modifications on this design: athletic or so-called cleated shoes like soccer, rugby, baseball and golf shoes have spikes embedded in the outsole to improve traction.[54]