A removable shoe insert, otherwise known as a foot orthosis, insole or inner sole accomplishes many purposes, including daily wear comfort, height enhancement, plantar fasciitis treatment, arch support, foot and joint pain relief from arthritis, overuse, injuries, leg length discrepancy, and other causes such as orthopedic correction and athletic performance.

Medical use of foot orthoses has been criticized as lacking evidence of benefit, and practice is very inconsistent: reputed podiatrists prescribe completely different orthoses for a single patient. Further, effect of a given design of orthosis varies significantly by patient, and standard practice to personalize prescription is not available. However, evidence is mixed: patients often report at least short-term improvements in comfort, and other studies have found effectiveness.