Metal oxidation is often unwanted--for example, in the case of corrosion--but under controlled conditions the oxidation of metals can be beneficial for the manufacture and performance of advanced materials9. In their Perspective, Over and Seitsonen provide a brief overview of the complex oxidation behavior of metal surfaces. They highlight the report by ThA¼rmeret al., who demonstrate the crucial role played by surface impurities in the oxidation of lead crystallites.