  Betelgeuse has fascinated people since they first looked at the sky. Here we
present a contemporary summary of the observations and theory that lead to our
understanding of Betelgeuse as a massive red supergiant doomed to collapse and
explosion. At only ~200 parsecs from Earth, Betelgeuse can be spatially
resolved yet uncertainties in its distance remain a critical impediment to
deeper understanding. The surface of Betelgeuse is rent with a complex
structure as deep convective eddies arise to the surface affecting most of its
measured physical properties. Determination of the equatorial rotation velocity
is critical since some current estimates indicate that Betelgeuse is rotating
anomalously rapidly, a property that cannot be explained by single-star
evolutionary models. Betelgeuse is also moving through space at relatively high
velocity that indicates that it received a boost, likely via collective
interaction with other stars in its birth cluster. A bow shock and other
structure in the direction of the star's motion suggest that it has affected
the organization of the circumstellar and interstellar medium. Betelgeuse
varies in brightness on a variety of time scales with 200, 400 and 2000 days
being prominent. Betelgeuse is probable to have been born in a binary system,
and the high space velocity and apparent rotation have been related to binary
star evolution. One possibility is that Betelgeuse underwent common envelope
evolution culminating in a final merger with the core of a massive primary.
Such merger models have been invoked to account for the anomalous rotation
velocity. Betelgeuse underwent a Great Dimming in 2020 that received widespread
attention. Explanations have focused on large cool spots on the surface and the
expulsion of a cloud of dust that obscured the surface. We sketch the nature of
the explosion to come and discuss perspectives for further research.
