Surface damage from sliding contact is related to the adhesion of mating surfaces in contact. This article describes the methods for evaluation of surface damage caused by sliding contact. It defines adhesive wear in terms of asperity, cold welding, galling, scuffing, seizure, and wear coefficient. The article discusses various galling testing methods, such as button-on-block galling test, pin-on-flat galling test, and threaded connection galling test. It provides an overview of fretting wear that occurs between two tight-fitting surfaces subjected to a cyclic, relative motion of extremely small amplitude. The article also reviews the fretting rig for investigating fretting wear.