During the last twenty-five years of scanning tunneling microscopy (STM), atomic resolution has become routine in studies of a wide range of materials. While less routine, atomic force microscopy (AFM) also can achieve atomic resolution, even on insulating surfaces. These two microscopy approaches have significantly advanced our understanding of the surface physics and chemistry of many important phenomena. A significant contribution of scanning probe microscopy is that it can characterize local properties as well as structure. Surprising levels of spatial resolution have been achieved in scanning probes that can access continuum properties such as resistance, capacitance, etc..