Particle physics studies the nature of particles. Particles are the constituents of matter and radiation. Particles are excitations of quantum fields. Particle physics is largely the study of the Standard Model particle contents and its extensions.
The Standard Model is used for classification for elementary particles. It describes strong, weak and electromagnetic interactions which use gauge bosons. Gauge bosons contains 24 fundamental particles. These particles are the constituents of all matter.
Particle physics has many practical applications today. In 1930, the first hand-held cyclotron was built; soon after more powerful accelerators were built. This allowed medical isotopes for research and treatment to be produced. Later applications of using particle physics technology were used in the treatment of cancer.