Electron microscopy, in its various forms and with myriad ancillary techniques, has become an indispensable characterization method for elucidating structure-function properties of nanoscale materials, molecular assemblies, and device architectures. The breadth of information that can be obtained is large and includes atomic-scale structure, electronic properties (e.g., density of states and plasmonic characteristics), and chemical composition (e.g., spatial element distribution, bond type, and oxidation state). Efforts in instrument development have led to significant advances in spatial, energy, and temporal resolutions; spherical-aberration correction enables formation of probe sizes well below 1 Å, monochromated electron guns can achieve energy resolutions below 100 meV, and pulsed-laser based methodologies that circumvent the millisecond resolution of digital detectors enable studies to be conducted on the femtosecond (i.e., 10-15 s) timescale. In situ and operando electron microscopy experiments – wherein materials are studied at elevated temperatures and pressures, immersed in liquids, and under electrical biasing or during mechanical deformation – are making possible the observation of atomic-scale morphological changes of catalyst particles in liquid phases, visualization of ferroelectric domain and domain wall dynamics, and the study of grain boundary and dislocation motion, to name a few. With its suite of microscopy capabilities, CEMS will continue to advance the field with innovative approaches to specimen preparation as well as via development of new techniques and instrumentation.