  Brane inflation is a specific realization of the inflationary universe
scenario in the early universe within the brane world framework in string
theory. The naturalness and robustness of this realistic scenario is explained.
Its predictions on the cosmological observables in the cosmic microwave
background radiation, especially possible distinct stringy features, such as
large non-Gaussianity or large tensor mode that deviates from that predicted in
the slow roll scenario, are discussed. Stringy KK modes as hidden dark matter
is also a possibility. Another generic consequence of brane inflation is the
production of cosmic strings towards the end of inflation. These cosmic strings
are nothing but superstrings stretched to cosmological sizes. The properties of
these cosmic superstrings and their subsequent cosmological evolution into a
scaling network open up their possible detections in the near future, via
cosmological, astronomical and/or gravitational wave measurements. At the
moment, cosmological data is already imposing strong constraints on the details
of the scenario. Finding distinctive stringy signatures in cosmological
observations will go a long way in revealing the specific brane inflationary
scenario and validating string theory as well as the brane world picture.
Precision measurements may even reveal the structures of the flux
compactification. Irrespective of the final outcome, we see that string theory
is confronting data and making predictions.
