Intro
This post reflects my personal point of view, based on what I have learned so far. It might change in the future in which case I will be more than happy to write this article again from a new perspective.
Quantum realm
When you scale down to a size of an atom, world around you suddenly starts to behave differently. Things become really strange and reality becomes hard to comprehend.
Electron, which you would imagine as a particle rotating around atom nucleus, always having speed and position, isn't particle at all. Well, that's not completely true and here is why.
Universe chose not to put everything on a finite position. Instead, Universe likes to play with probabilities. So instead saying your electron can be found at position defined by (x, y, z) coordinates, electrons position is somewhere in the area of probability defined by the wave function. Some parts of this area have higher probability to contain electron, other have lower.
Probability cloud depiction
Areas in this image, which are darker, have higher probability to contain electron and brighter ones can rarely contain an electron.
But wait! So electron is somewhere inside this area, and is most likely to be inside those dark spots?
The answer is no!
Electron is actually in all these places at once and nowhere. Only when you really observe the electron, universe decides where it should be located.
Scientists call this collapse of a wave function, and I would call it creation on demand. So it became a particle just by act of observation. You wanted to see it, and Universe gave you a particle.
Universe is stingy and super fast
As you saw previously, there is no electron, there is just a probability assigned to it's possible location. If there is nothing to observe it, it will stay like this forever, just a probability information, nothing more.
Why I insulted Universe saying that it's stingy. Universe doesn't give you anything unless you ask for it (look at it).
You are an observer and without you, Universe you know does not exist.
Universe is more that we can see
Human senses are limited, they are good enough for survival, not for seeing the whole picture. Our sight is limited to only a part of light spectrum. Having this said, Universe is more that we can see with our eyes, and more than we can measure with our instruments. What lies behind this beautiful world and runs everything is impossible for us to discover. The reality we see is simply a response. We query Universe and it gives us response which we interpret as our reality. If we query it in a different way it will produce different response (reality) but we never get to see the full reality, only what we can query.