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. 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.
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 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).
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.
The midsole is the layer in between the outsole and the insole, typically there for shock absorption. Some types of shoes, like running shoes, have additional material for shock absorption, usually beneath the heel of the foot, where one puts the most pressure down. Some shoes may not have a midsole at all. The heel is the bottom rear part of a shoe. Its function is to support the heel of the foot. They are often made of the same material as the sole of the shoe. This part can be high for fashion or to make the person look taller, or flat for a more practical and comfortable use. On some shoes the inner forward point of the heel is chiseled off, a feature known as a “gentleman’s corner”. This piece of design is intended to alleviate the problem of the points catching the bottom of trousers.
The upper helps hold the shoe onto the foot. In the simplest cases, such as sandals or flip -flops, this may be nothing more than a few straps for holding the sole in place. Closed footwear, such as boots, trainers and most men’s shoes, will have a more complex upper. This part is often decorated or is made in a certain style to look attractive. The upper is connected to the sole by a strip of leather, rubber, or plastic that is stitched between it and the sole, known as a welt.
Most uppers have a mechanism, such as laces, straps with buckles, zippers, elastic, Velcro straps, buttons, or snaps, for tightening the upper on the foot. Uppers with laces usually have a tongue that helps seal the laced opening and protect the foot from abrasion by the laces. Uppers with laces also have eyelets or hooks to make it easier to tighten and loosen the laces and to prevent the lace from tearing through the upper material. An aglet is the protective wrapping on the end of the lace.
The vamp is the front part of the shoe, starting behind the toe, extending around the eyelets and tongue and towards back part of the shoe.
The medial is the part of the shoe closest to a person’s center of symmetry, and the lateral is on the opposite side, away from their center of symmetry. This can be in reference to either the outsole or the vamp. Most shoes have shoelaces on the upper, connecting the medial and lateral parts after one puts their shoes on and aiding in keeping their shoes on their feet. In 1968, Puma SE introduced the first pair of sneakers with Velcro straps in lieu of shoelaces, and these became popular by the 1980s, especially among children and the elderly.
The toe box is the part that covers and protects the toes. People with toe deformities, or individuals who experience toe swelling (such as long distance runners) usually require a larger toe box.