Although the benefits of operating the scanning electron microscope at low beam energies have been evident since the earliest days of the instrument, the successful utilization of the SEM under these conditions has required the development of high brightness field emission electron source, advanced lenses, and clean vacuums. As these technologies became available the level at which imaging became regarded as “low energy” has fallen from 10 keV, first to 5 keV, and more recently to 1 keV. At this energy state of the art, instruments can now provide an excellent balance between resolution - which becomes worse with decreasing energy - and desirable goals such as the minimization of sample charging and the reduction of macroscopic radiation damage - which tend to become more challenging as the energy is increased.