This document provides an overview of pes planus (flat foot) including the anatomy of the foot arches, definition and causes of pes planus, and discussions of common causes such as flexible flat foot, congenital vertical talus, tarsal coalition, and posterior tibial tendon disorder. Flexible flat foot is usually asymptomatic in infants and children. Congenital vertical talus is a rigid deformity characterized by dorsal dislocation of the talonavicular joint. Treatment involves serial casting or surgery to gradually correct contractures and restore normal anatomy.