The reader is holding the first volume of a three-volume textbook on sol- state physics. This book is the outgrowth of the courses I have taught for many years at Eötvös University, Budapest, for undergraduate and graduate students under the titles Solid-State Physics and Modern Solid-State Physics. The main motivation for the publication of my lecture notes as a book was that none of the truly numerous textbooks covered all those areas that I felt should be included in a multi-semester course. Especially, if the course strives to present solid-state physics in a unified structure, and aims at d- cussing not only classic chapters of the subject matter but also (in more or less detail) problems that are of great interest for today’s researcher as well. Besides, the book presents a much larger material than what can be covered in a two- or three-semester course. In the first part of the first volume the analysis of crystal symmetries and structure goes into details that certainly cannot be included in a usual course on solid-state physics. The same applies, among others, to the discussion of the methods used in the determination of band structure,the properties of Fermi liquids and non-Fermiliquids, andthe theory of unconventional superconductors in the second and third volumes. These parts canbe assignedas supplementary reading for interested students, or can be discussed in advanced courses.