Dark energy, gravitation and supernovae

The discovery of the acceleration of the rate of expansion of the universe fosters new explorations of the behaviour of gravitation theories in the cosmological context. Either the GR framework is valid but a cosmic component with a negative equation of state is dominating the energy-matter contents or the universe is better described at large by a theory that departs from GR. In this review, we address theoretical alternatives that have been explored through supernovae.