  Moir\'e superlattices - periodic orbital overlaps and lattice-reconstruction
between sites of high atomic registry in vertically-stacked 2D layered
materials - are quantum-active interfaces where non-trivial quantum phases on
novel phenomena can emerge from geometric arrangements of 2D materials, which
are not intrinsic to the parent materials. Unexpected distortions in
band-structure and topology lead to long-range correlations, charge-ordering,
and several other fascinating quantum phenomena hidden within the physical
space between the (similar or dissimilar) parent materials. Stacking, twisting,
gate-modulating, and optically-exciting these superlattices open up a new field
for seamlessly exploring physics from the weak to strong correlations limit
within a many-body and topological framework. It is impossible to capture it
all, and the aim of this review is to highlight some of the important recent
developments in synthesis, experiments, and potential applications of these
materials.
