The reader is holding the ?rst 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 Eotvos 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 uni?ed structure, and aims at...