  X-ray microscopy has been an indispensable tool to image nanoscale properties
for materials research. One of its recent advances is to extend microscopic
studies to the time domain for visualizing the dynamics of nanoscale phenomena.
Large-scale x-ray facilities have been the powerhouse of time-resolved x-ray
microscopy. Their upgrades including a significant reduction of the x-ray
emittance at storage rings and fully coherent ultrashort x-ray pulses at free
electron lasers, will lead to new developments in instrumentation and open new
scientific opportunities for x-ray imaging of nanoscale dynamics with the
simultaneous attainment of unprecedentedly high spatial and temporal
resolutions. This review presents recent progress in and the outlook for
time-resolved x-ray microscopy in the context of ultrafast nanoscale imaging
and its applications to condensed matter physics and materials science.
