Particle physics is a branch of physics that is involved in the study of the elementary constituents of matter and radiation, and the interactions between them. It is also referred to as high energy physics because many subatomic particles are absent in nature under normal circumstances but can be created and detected during energetic collisions of other particles. In particle physics, large particle accelerators are used for fundamental research. Particle accelerator is a machine that uses an electric field to speed-up and increase the energy of a beam of particles and the magnetic fields steer and focus them. They are used to study and explore the structure of the atomic nucleus and other aspects of particle physics. The modern particle physics research is focused on subatomic particles such as electrons, protons and neutrons. It also studies particles such as photons, neutrinos and muons, which are produced by radioactive and scattering processes. This book contains studies on the theory and applications of particle physics. It attempts to further enlighten the readers about the new concepts in this field.