  One of the great endeavors of the past decade has been the evaluation of
different observational techniques for measuring dark energy properties and of
theoretical techniques for constraining models of cosmic acceleration given
cosmological data. This chapter reviews a few of the key developments,
promises, and cautions for revealing dark energy. We also present a few new
calculations, on direct detection of acceleration through redshift drift, the
minimum uncertainty in the equation of state, and testing gravity.
