Quantum physics is the study of quantization in physics.. . In classical physics, systems are considered to be continuous. What this means is that if you look at electrons flowing through your monitor, for example, classical physics treats those electrons as a big "electron ocean" made of one giant liquid electron.. . Quantum physics takes into account that each electron exists in a separate physical location from each other - that each one is a quantum particle - and that nothing is continuous in reality.. . And so if a small quantum particle gains a quanta of energy (say it absorbs some light, for example) it may increase in energy by that amount. It cannot increase in energy by any more or less than a quanta, and so there is no possible way for an electron to gain "half" of a whole quanta of energy.. . Quantum physics is an open-ended science currently. What this means is that no one has a solid explanation of why nature should work in this fashion. In the mathematical formalism of quantum physics, there is a formula called the "wave function" that is associated with each particle. The wave function accurately predicts quantum experiments with 99.99% accuracy. The only problem, though, is that no one knows exactly what the wave function is - we only know that it works.