Boronizing is a case hardening process for metals to improve the wear life and galling resistance of metal surfaces. Boronizing can be carried out using several techniques. This article discusses the powder pack cementation process for carrying out boronizing. It describes the structures of boride layers in ferrous materials and boride-layer structures in nickel-base superalloys. The primary reason for boriding metals is to increase wear resistance against abrasion and erosion. The article reviews the wear resistance and coefficient of friction of boride layers, as well as galling resistance of borided surfaces. It concludes with a discussion on boronizing plus physical vapor deposition (PVD) overlay coating.