Superconductors are the materials which show a sudden drop of electrical resistance at a certain temperature when cooled below room temperature. While most superconductors of early generation were low T_C materials, next generation superconductors, layered oxides based on perovskite structure, were called as high T_C as materials showing T_C in the excess of liquid N₂ temperature. These have been successfully fabricated in various forms and examined at various places across the world. While the BCS theory explains the origin the superconductivity in the low T_C superconductors quite well, a well agreed theory for the high T_C ceramic oxides is yet to evolve. These have found applications in magnetically levitated trains and magnetic resonance imaging for medical applications.