The development of aberration correction for electron microscopy has greatly increased our ability to characterize materials at the atomic scale. The same technological advances that have extended the resolution limit to 0.5Å have also made it possible to record images with better signal-to-noise and at faster rates. Coupled with MD simulations, this new capability has allowed us to unravel dynamic events that were previously inaccessible. Among such events, the atomic displacements involved in the motion of steps and facets are of key importance for our understanding of microstructural evolution in polycrystalline materials. This talk will highlight our recent studies on the atomic structure and dynamics of steps and facets during grain boundary migration in gold bicrystals.