Outsole

An outsole is the outermost bottom component of a shoe or boot that makes contact with the ground. It protects the inner parts of the footwear, provides traction, and contributes to durability, stability, and sometimes insulation. The outsole is distinct from the midsole, which cushions and supports the foot, and from the insole, which lies directly under the foot.

Outsoles are made from various materials, with rubber being the most common. Natural or synthetic rubber offers wear resistance and grip; other polymers such as polyurethane, EVA, and thermoplastic elastomers are used for lighter weight or specific performance traits. Leather is sometimes used for dress soles, but typically requires treatment for grip and durability. Outsoles may be solid or feature multiple layers, and the attachment to the midsole can be cemented, stitched, welded, or vulcanized.

Traction is largely determined by tread patterns: lug outsoles used for hiking and work boots provide deep grip; running and basketball shoes may use patterned grooves or herringbone designs for multidirectional grip; smooth or lightly textured soles are common on dress shoes. Some outsoles include specialized features such as siping for wet surfaces, or high-friction compounds for chemical resistance.

Care and maintenance involve keeping the outsole clean and dry, inspecting for wear, and replacing or resoling when tread is worn to the point of reduced traction or when the sole detaches from the upper. Advances in sustainability have led to the use of recycled rubber and other reclaimed materials in some outsoles, with ongoing work to improve lifecycle durability.