The branch of physics concerned with the microscopic and macroscopic properties of matter is known as condensed matter physics. It specifically studies condensed phases, which have a high population of constituents, and interact strongly with each other. It builds on the principles of quantum mechanics, electromagnetism and statistical mechanics to study all condensed phases of matter. Modern theoretical condensed matter physics involves the application of numerical computation and mathematical tools to understand high-temperature superconductivity, gauge symmetries and topological phases. The aim of this book is to present researches that have transformed this discipline and aided its advancement. It presents the complex subject of condensed matter physics in the most comprehensible and easy to understand language. The readers would gain knowledge that would broaden their perspective about this field.