This document defines and distinguishes between valgus and varus deformities by describing how the distal end of the bone is positioned relative to the body's midline. Valgus refers to when the distal end moves laterally away from the midline, while varus means it moves medially towards the midline. Examples provided are genu valgus and genu varus at the knee, as well as coxa valgus and coxa varus at the hip.