Solids consist of densely packed atoms whose interactions give rise to various properties such as magnetic, optical, thermal, mechanical, and electrical characteristics. The arrangement of atoms in a solid can be either in a regular geometric pattern, forming a crystal, or irregularly in an amorphous solid. The study of these aspects of solids fall within the purview of solid state physics, a branch of condensed matter physics. Solid state physics employs methodologies from electromagnetism, quantum mechanics, crystallography, and metallurgy to understand solids. Techniques like neutron diffraction, X-ray crystallography, and electron diffraction are used to investigate the crystalline structure of materials. Additionally, solid state physics explores phenomena such as quasicrystals, high-temperature superconductivity, and strongly correlated materials. It finds practical applications in the development and utilization of semiconductors and transistors. This book is a compilation of chapters that discuss the most vital concepts and theories in the field of solid state physics. The topics covered herein deal with the core subject of solid state physics. This book is an essential guide for both academicians and those who wish to pursue this discipline further.