The Nuclear Spectroscopic Telescope Array, the first focusing high-energy X-ray  (3 – 79 keV) telescope in orbit, extends sensitive X-ray observations above the band pass where Chandra and XMM-Newton operate.   With an unprecedented combination of sensitivity, spectral and imaging resolution above 10 keV, NuSTAR is advancing our understanding of black holes, neutron stars, and supernova remnants.  I will describe the mission, and present science highlights from the two-year baseline mission.