  We present an overview of the theoretical understanding of Hofstadter
butterflies in monolayer and bilayer graphene. After a brief introduction on
the past work in conventional semiconductor systems, we discuss the novel
electronic properties of monolayer and bilayer graphene that helped to detect
experimentally the fractal nature of the energy spectrum. We have discussed the
theoretical background on the Moir\'e pattern in graphene. This pattern was
crucial in determining the butterfly structure. We have also touched upon the
role of electron-electron interaction in the butterfly pattern in graphene. We
conclude by discussing the future prospects of butterfly search, especially for
interacting Dirac fermions.
