The curiosity of mankind, which started with the understanding and interpretation of his environment, has made enough progress to examine atomic-sized objects in the twenty-first century. The findings obtained by the analysis of substances, especially solid substances, at the atomic level, have made these materials indispensable materials of life in the modern world. Modern Solid State Electronics devices and integrated circuits usually encompass small sizes of metal, semiconductor or insulator materials, which are three different forms of solids. Particularly, semiconductor materials have a very important place in the field of electronics in that their electrical, optical or magnetic properties can be changed by doping. This book has been prepared to cover the basic topics in Solid State Physics-I and Solid State Physics-II courses, which are compulsory two semesters in all physics departments of our universities. In addition, considering the importance of semiconductors in their technological applications, it also includes the amplification techniques, characterization and some basic applications of semiconductors for students specializing in semiconductor physics. Nanostructures and liquid crystals, which are current topics of the modern world, also constitute the last two chapters of the book.