The past twenty years or so have seen dramatic development of the experimental and theoretical tools available to study the surfaces of solids at the molecular (“atomic resolution”) scale. On the experimental side, two areas of development well illustrate these advances. The first concerns the high intensity photon sources associated with synchrotron radiation; these have both greatly improved the surface sensitivity and spatial resolution of already established surface spectroscopic and diffraction methods, and enabled the development of new methods for studying surfaces. These have included the techniques of X-ray Absorption Spectroscopy (for example, EXAFS and XANES; see Wincott and Vaughan 2006, this volume) which can be used to probe the molecular scale environment of atoms at the surface of a particulate sample in contact with a fluid. The second centers on the scanning probe microscopy (SPM) techniques initially developed in the 1980’s with the first scanning tunneling microscope (STM) and atomic force microscope (AFM) experiments. The direct “observation” of individual atoms at surfaces made possible with these methods has truly revolutionized surface science. As well as providing insights into the crystallography and morphology of the pristine surface, the new range of SPM methods has enabled real time and in situ observations of surfaces during reaction with gases and fluids. On the theoretical side, the availability of high performance computers coupled with advances in computational modeling has provided powerful new tools to complement the advances in experiment. Particularly important have been the quantum mechanics based computational approaches such as density functional theory (DFT), which can now be easily used to calculate the equilibrium crystal structures of solids and surfaces from first principles, and to provide insights into their electronic structure. There have also been important advances in the use of more empirical or semi-empirical computational methods, both those based on …