The generation of zinc and zinc alloy coatings on steel is one of the commercially most important processing techniques used to protect steel components exposed to corrosive environments. From a technological standpoint, the principles of galvanizing have remained unchanged since this coating came into use over 200 years ago. However, because of new applications in the automotive and construction industry, a considerable amount of research has recently occurred on all aspects of the galvanizing process and on new types of Zn coatings, This review will discuss the metallurgy of zinc-coated steel from a scientific standpoint to develop relationships to practical applications. Hot-dip zinc coating methods, i.e. batch and continuous processes, will first be reviewed along with Fe-Zn phase equilibria and kinetics. Commercially, the addition of aluminum to the zinc bath results in three important types of coatings, galvanized, galfan and galvalume, and produces complex reactions at the coating/substrate interface. Fe-Zn-Al equilibrium will be reviewed in the light of recent studies of solubility and inhibition layer formation and breakdown. The effect of steel substrate composition on these reactions will also be critically analyzed. The overlay coating formation, or the coating alloy, is specifically chosen for its desired properties. The morphology of the galvanize, galfan and galvalume coating overlays will be reviewed, as well as the effect of heat treatment to produce a galvanneal coating. Finally, the effect of the microstructures of these coatings on the important properties of corrosion, formability, weldability and paintability will be discussed.