Physics is the field of science that studies the physical world. From the large (galaxies, planets, etc) to the small (how proteins fold, atoms, etc) physics plays a role. It is a natural science that studies the properties of matter, motion, force, energy, space and time.
Physics has a number of divisions or sub-categories. Each of these are more focused areas of study.
Quantum Physics, the study of the quantum world (smaller than an atom).
Particle Physics, the study of atomic and quantum particles such as electrons, protons, gluons and neutrinos.
Theoretical Physics, this is the branch of physics which deals in theory. It's generally at the forefront of physics and thought. After a theory has been shown possible that theory may move into another branch of physics.
Astrophysics, studies aspects of stars, galaxies and space. It is closely linked with astronomy.
Medical Physics, the study of physics and it's role in medicine. For example, radiation therapy, the development of certain medicines and areas of neurology all require a deep understanding of physics.
Geophysics, the study of physics as it relates to Earth.
Mathematical physics, General & Special Relativity, Classical Mechanics, Thermodynamics, Electromagnetism and Temporal Mechanics are all other divisions of physics.
Physics is a branch of science that deals with mater and motion; it also focused on the "Fundamental Laws of the Universe."
Two Main Branches
1. Pure Physics
2. Applied Physics
Pure Physics
1. Mechanics - study of forces & energy on bodies of fluids at rest or in motion.
2. Optics - study of not only light, but also the electromagnetic spectrum just above x-rays to just below microwaves.
3. Thermodynamics - study of heat in terms of molecular motion.
4. Quantum Physics - study based on the theory of electromagnetic wave (matter interaction.
5. Plasma - study of the 4th state of matter, ionized particles & their properties.
6. Electromagnetism
Applied Physics
1. Engineering - harnessing of materials, forces & energy so they can be of use to man
2. Optometry - knowledge of optics as applied to vision instruments