Matter that makes up every known substance to man occurs in nature in three distinct forms – solid, liquid and gas. Irrespective of their classification all forms of matter consist of molecules which can be further classified into atoms. These atoms interact intensely producing the mechanical, thermal, electrical, magnetic and optical properties of the state of matter. Depending on the material involved and the conditions in which it was formed, the atoms may be arranged in a regular, geometric pattern or irregularly. The bulk of solid-state physics as a general theory and not really a proven form of research is focused on crystals. Primarily, this is because the periodicity of atoms in a crystal — its dening characteristic – facilitates mathematical modelling. The book explores such concepts along with other related subject matter. Table of contents – States of Matter, Atomic Concept, Atomic Physics, Radioactivity, Atomic Structure, Electrostatic Force, Matter and Magnetic Force, Electric Fields, Review of Energy Dispersion Relations in Solids.