  Inflation may provide unique insight into the physics at the highest
available energy scales that cannot be replicated in any realistic terrestrial
experiment. Features in the primordial power spectrum are generically predicted
in a wide class of models of inflation and its alternatives, and are
observationally one of the most overlooked channels for finding evidence for
non-minimal inflationary models. Constraints from observations of the cosmic
microwave background cover the widest range of feature frequencies, but the
most sensitive constraints will come from future large-scale structure surveys
that can measure the largest number of linear and quasi-linear modes.
