The book targets a broad readership. First of all, it targets young researchers (postgraduate students) in solid state physics (both physicists and theoretical chemists) as it contains a wide and comprehensive coverage of all important branches of the subject including an up-to-date survey of recent revolutionary advances in quantum mechanics which have made it possible not only to calculate many properties of molecules and solids in close agreement with experiment, but to make reliable predictions in cases when a direct experiment is not possible (e.g. the Earth core). Secondly, it should be a valuable asset to established researches in the areas of materials science, solid-state physics and chemistry due to very detailed explanations of a wide range of phenomena ranging from symmetry, lattice vibrations, electronic structure and superconductivity to magnetic and dielectric properties. Rigour and detail in explaining complicated mathematical techniques and in providing derivations when talking of various physical concepts are essential for those who would like to really understand things they have never had a chance to. Because of that and of the fact that the book contains a lot