  The Kepler spacecraft, whose single instrument was a 0.95 m diameter
wide-field telescope, operated in a heliocentric orbit for nearly a decade,
returning a wealth of data that have revolutionized exoplanet science. Kepler
data have been used to discover thousands of planets, including hundreds of
multi-planet systems. Kepler discoveries have greatly expanded the diversity of
known exoplanets and planetary system properties. Moreover, Kepler has provided
the best estimates of exoplanet occurrence rates as functions of planetary
sizes, orbital periods and stellar type, with precise values for planets with
$P \lesssim 1$ yr. We provide herein an overview of the mission and its major
findings regarding the occurrence rates of planets, the mass-radius
relationship for exoplanets and the architectures of planetary systems.
