Topological insulators(TIs) are the materials which exhibit insulating behaviour in the bulk and conducting states at the edge/surface. Since the discovery of integer quantum Hall effect(IQHE), efforts have been made to invent the materials which should possess the intrinsic magnetic field and must preserve the time reversal symmetry. In this regard, theoretical models proposed by F.D.M.Haldane and Kane-Mele helped in the realisation of TIs. Ever since an abundant number of TIs were discovered both experimentally and theoretically. In the first part of my talk, I mainly focus on the historical developments and brief the mathematical formulations of TIs. In the remaining part, I will discuss topological insulating properties in the bismuth based oxides and halide perovskites.