According to About.com, physics is the study of matter, energy and the way they interact. Physics is a natural science that also encompasses concepts like force and motion. The primary goal of physics is to understand how the universe behaves.
The study of physics is essentially the study of everything. Energy can take the form of light, motion, gravity, electricity, radiation and many others. Matter is an incredibly broad term that encompasses everything from subatomic particles like quarks to unfathomably large galaxies. Astrophysics and quantum physics are the branches of physics that deal with extremely large and small objects, respectively.
Out of all of the academic disciplines, physics is considered one of the oldest. Physics intersects with many other interdisciplinary sciences – like astronomy, quantum chemistry and biophysics. Physics plays an important role in the development of mathematics, just as mathematics contributes a great deal to the continued evolution of physics. Modern physics even opens up new ways of thinking in philosophy.
The study of physics contributes a great deal to the creation of new technologies. Industrialization has its roots in thermodynamics, and inventions like computers, television sets and nuclear weapons would not exist without theoretical breakthroughs in electromagnetism and nuclear physics.