  Near a magic twist angle, bilayer graphene transforms from a weakly
correlated Fermi liquid to a strongly correlated two-dimensional electron
system with properties that are extraordinarily sensitive to carrier density
and to controllable environmental factors such as the proximity of nearby gates
and twist-angle variation. Among other phenomena magic-angle twisted bilayer
graphene hosts superconductivity, interaction induced insulating states,
magnetism, electronic nematicity, linear-in-T low-temperature resistivity, and
quantized anomalous Hall states. We highlight some key research results in this
field, point to important questions that remain open, and comment on the place
of magic angle twisted bilayer graphene in the strongly correlated quantum
matter world.
