This treatise on Superconductivity provides a comprehensive introduction of the vast field. The content covers experimental as well as theoretical research in the field providing a clear interrelationship with experimental problems. The discovery of high-Tc cuprates, Iron-pnictide superconductors, Itinerant ferromagnetic superconductors, Nanostructured superconductors, etc. opened a new class of anisotropic materials in this field. The discovery of these materials has posed two problems of making high-Tc materials available to technology at room temperature on one hand and of exploring the possible mechanism of High-Tc and other anisotropic superconductors. The beginning of 21st century sees superconductor applications reaching important milestones.