The course deals with the basics of superconductivity, including Meissner effect, electrodynamic response, -type-I and type-II superconductors etc. BCS theory, the only microscopic theory of superconductivity is discussed in details with a view to understand superconducting transition temperature and its relation to the pairing gap. Further Ginzburg Landau theory is introduced which is a phenomenological theory that is applicable in general to second order phase transitions. A few experimental methods to explore the superconducting gap are discussed. Unconventional superconductivity is elaborately talk about with regard to the unusual normal phase of the high Tc cuprates and ramification due to the breakdown of Landau's Fermi liquid theory therein is emphasized. Finally Josephson effect is introduced and its applications to superconducting circuits are studied. Special emphasis is given to DC SQUID which uses Josephson junctions and has a variety of applications, such as sensors, amplifiers, magnetometers etc.