  The Outer Solar System Origins Survey (OSSOS), a wide-field imaging program
in 2013-2017 with the Canada-France-Hawaii Telescope, surveyed 155 deg$^{2}$ of
sky to depths of $m_r = 24.1$-25.2. We present 838 outer Solar System
discoveries that are entirely free of ephemeris bias. This increases the
inventory of trans-Neptunian objects (TNOs) with accurately known orbits by
nearly 50%. Each minor planet has 20-60 Gaia/Pan-STARRS-calibrated astrometric
measurements made over 2-5 oppositions, which allows accurate classification of
their orbits within the trans-Neptunian dynamical populations. The populations
orbiting in mean-motion resonance with Neptune are key to understanding
Neptune's early migration. Our 313 resonant TNOs, including 132 plutinos,
triple the available characterized sample and include new occupancy of distant
resonances out to semi-major axis $a \sim 130$ au. OSSOS doubles the known
population of the non-resonant Kuiper belt, providing 436 TNOs in this region,
all with exceptionally high-quality orbits of $a$ uncertainty $\sigma_{a} \leq
0.1\%$; they show the belt exists from $a \gtrsim 37$ au, with a lower
perihelion bound of $35$ au. We confirm the presence of a concentrated
low-inclination $a\simeq 44$ au "kernel" population and a dynamically cold
population extending beyond the 2:1 resonance. We finely quantify the survey's
observational biases. Our survey simulator provides a straightforward way to
impose these biases on models of the trans-Neptunian orbit distributions,
allowing statistical comparison to the discoveries. The OSSOS TNOs,
unprecedented in their orbital precision for the size of the sample, are ideal
for testing concepts of the history of giant planet migration in the Solar
System.
