Flatfoot is a progressive deformity with a collapse of the foot. Its therapeutic approach has undergone a conceptual shift. Initially focused on posterior tibial tendon insufficiency, it is now defined by a sum of anatomical alterations resulting in a three-dimensional deformity. If the deformity is symptomatic, we look for hindfoot valgus, forefoot abduction and varus, as well as valgus ankle instability. The clinical rigidity of the deformities and the weight-bearing radiological examinations help guide treatment. Although plantar supports and rigid orthoses are sufficient for mild cases, surgical treatment using bone, ligament, tendon or even prosthetics procedures are the final stage of management for severe cases.