Quantum physics is a physical science dealing with the behaviour of matter and electromagnetic waves on the scale of atoms and subatomic particles. It also forms the basis for the contemporary understanding of how large objects such as stars and galaxies, and cosmological events such as the Big Bang, can be analyzed and explained. Its success is due to its accurate prediction of the physical behaviour of systems, including systems where Newtonian mechanics fails. This difference between the success of classical and quantum mechanics is most often observed in systems at the atomic scale or smaller, or at very low or very high energies, or at extremely low temperatures. Quantum mechanics is the basis of modern developments in chemistry, molecular biology, and electronics, and the foundation for the technology that has transformed the world in the last fifty years.