Late time cosmic acceleration: ABCD of dark energy and modified theories
  of gravity
  We briefly review the problems and prospects of the standard lore of dark
energy and notice that the cosmological constant problems are often over
emphasized. In order to keep the discussion pedagogical aimed at a wider
audience, we have avoided technical complications in several places and
resorted to heuristic arguments based on physical perceptions. We presented
underlying ideas of modified theories based upon chameleon mechanism and
Vainshtein screening. We have given a lucid illustration of recently
investigated ghost free non linear massive gravity. Again we have sacrificed
rigor and confined to the basic ideas that led to the formulation of $dRGT$.
The review ends with a brief discussion on the difficulties of the theory
applied to cosmology with an optimism that a consistent solution of the problem
is round the corner.
