  Chiral symmetry, fundamental in the physics of graphene, guarantees the
existence of topologically stable doubled Dirac cones and anomalous behaviors
of the zero-energy Landau level in magnetic fields. The crucial role is
inherited in the optical responses and many-body physics in graphene, which are
explained in this paper. We also give an overview of multilayer graphene from
the viewpoint of the optical properties and their relation with the chiral
symmetry.

Mesoscale and Nanoscale Physics;Strongly Correlated Electrons