  Understanding how massive stars die as supernovae is a crucial question in
modern astrophysics. Supernovae are powerful stellar explosions and key drivers
in the cosmic baryonic cycles by injecting their explosion energy and heavy
elements to the interstellar medium that forms new stars. After decades of
effort, astrophysicists have built up a stand model for the explosion mechanism
of massive stars. However, this model is challenged by new kinds of stellar
explosions discovered in the recent transit surveys. In particular, the new
population called superluminous supernovae, which are a hundred times brighter
than typical supernovae, is revolutionizing our understanding of supernovae.
New studies suggest the superluminous supernovae are associated with the
unusual demise of very massive stars and their extreme supernovae powered by
the radioactive isotopes or compact objects formed after the explosion.
Studying these supernovae fills a gap of knowledge between the death of massive
stars and their explosions; furthermore, we may apply their intense luminosity
to light up the distant universe. This paper aims to provide a timely review of
superluminous supernovae physics, focusing on the latest development of their
theoretical models.
