  The Origins Space Telescope, one of four large Mission Concept studies
sponsored by NASA for review in the 2020 US Astrophysics Decadal Survey, will
open unprecedented discovery space in the infrared, unveiling our cosmic
origins. We briefly describe in this article the key science themes and
architecture for OST. With a sensitivity gain of up to a factor of 1,000 over
any previous or planned mission, OST will open unprecedented discovery space,
allow us to peer through an infrared window teeming with possibility. OST will
fundamentally change our understanding of our cosmic origins - from the growth
of galaxies and black holes, to uncovering the trail of water, to life signs in
nearby Earth-size planets, and discoveries never imagined. Built to be highly
adaptable, while addressing key science across many areas of astrophysics, OST
will usher in a new era of infrared astronomy.

Instrumentation and Methods for Astrophysics;Earth and Planetary Astrophysics;Astrophysics of Galaxies;Solar and Stellar Astrophysics