This is an introductory book on solid state physics. It is a translation of a Hebrew version, written for the Open University in Israel. Aimed mainly for self-study, the book contains appendices with the necessary background, explains each calculation in detail and contains many solved problems. The bulk of the book discusses the basic concepts of periodic crystals, including lattice structures, radiation scattering off crystals, crystal bonding, vibrations of crystals, and electronic properties. On the other hand, the book also presents brief reviews of advanced topics, e.g. quasicrystals, soft condensed matter, mesoscopic physics and the quantum Hall effect. There are also many specific examples drawn from modern research topics, e.g. perovskite oxides relevant for high temperature superconductivity, graphene, electrons in low dimensions and more.