Principles of Solid State Physics presents a unified treatment of the basic models used to describe the solid state phenomena.This book is divided into three parts. Part I considers mechanical or geometrical properties that are describable by a lattice of mass points. What happens if the electric charge and magnetic moment are to be associated with the lattice points is explained in Part II. Part III discusses the application of the band theory and imperfections in solids.This publication is recommended for a one-semester senior course in solid state physics for students majoring in physics, chemistry, and electrical engineering.