This book describes the elementary concepts of superconductivity and discusses the topics on flux-lattice melting, magnetization including the para-Meissner effect, microwave absorption, a.c. resistivity along with the London penetration depth, the Mossbauer effect, levitation, fractal and nuclear magnetic resonance. There are appendices covering superconducting compounds the isotope effect, symmetries, the pseudogap relativistic superconductivity, the Cherenkov effects and soft vortices. Also included is an appendix on the quantum Hall effect. In all of the chapters the theoretical description is supported by experimental data. Several of the topics discusses here cannot be found in the other books on this subject.