The field that focuses on examining atoms as self-contained systems composed of electrons and a nucleus is atomic physics. In this discipline, atomic models typically depict a single nucleus encircled by one or more bound electrons. These electrons occupy discrete shells around the nucleus and are considered to be in bound states. Atomic physics involves investigating phenomena such as ionization and excitation caused by photons and collisions with atomic particles. Ionization, for instance, occurs when an atom or molecule gains or loses electrons, resulting in a negative or positive charge. This branch of physics is closely interconnected with the fields of molecular and optical physics. This book is a compilation of chapters that discuss the most vital concepts in the field of atomic physics. The topics covered herein deal with the core aspects of this area. It will also serve as a reference guide for students and academicians.