  Complex oxide interfaces have been one of the central focuses in condensed
matter physics and material science. Over the past decade, aberration corrected
scanning transmission electron microscopy and spectroscopy has proven to be
invaluable to visualize and understand the emerging quantum phenomena at an
interface. In this paper, we briefly review some recent progress in the
utilization of electron microscopy to probe interfaces. Specifically, we
discuss several important challenges for electron microscopy to advance our
understanding on interface phenomena, from the perspective of variable
temperature, magnetism, electron energy loss spectroscopy analysis, electronic
symmetry, and defects probing.
