In the world of our scale - planets, humans, ants - could follow Newton's laws: if we know the position of something, direction, and speed, we can determine its past and future position (ignoring the variables, of course). The billiard balls follow a predictable behavior and everything else also seems to respect the laws of motion and Einstein's Theory of Relativity.
Quantum mechanics can determine with complete accuracy the microcosms behavior, but no one can explain this behavior. We can say that we enjoyed the success that the theory had (all our digital technology is based on quantum mechanics, like many other relevant techniques), but the microcosms behave in such a strange way that our shared sense not able to understand.
Well, what about the microscopic world? How to behave atoms and subatomic particles? The behavior of the most basic units of nature can be considered schizophrenic: subatomic particles can be in two places at the same time, behave both as waves and as particulate matter and can go from point A to get to B ... before leaving the; can also go from point A to the point B, C, D, E (etc., etc.) at the same time! Never able to determine with complete accuracy where you are and where you're going a subatomic particle; if we know the position of an electron, for example, we lose the information of its direction, and vice versa. There is always an uncertainty (Heisenberg Uncertainty Principle) in the microscopic world. To help the party, subatomic particles are in perpetual motion and may disappear from your room and appear in China or Jupiter ... instantly!
