We see objects only because they all reflect light.
As you know things consist of molecules, and molecules - of atoms...
Each atom consists of a nucleus (made of protons and neutrons) and then there are the electrons orbiting around it.
For example let's take the simplest atom, the atom of Hydrogen (H). It consists of one proton and one electron spinning around it. This electron can spin on 6 levels over the nucleus. In static position it spins on the closest first level.
As soon as it gets energy – any energy - heat, power, light, it moves on to the next second level. Then it progresses to the third, fourth, fifth and to the sixth levels. On the sixth level it stays for 8 to 10 s. and then “goes back”.
At this moment, when the electron moves from the higher level to the lower one, it gets rid of the energy it got earlier.
When it reaches our eyes we see this radiation of energy like a beam of light.
Do you see this? It’s only ONE atom, with only one electron, with only 6 orbits. Imagine how much beams of light other molecules radiate, the molecules with more than one electron: 2, 3, 5, 8, 13, 21 and so on.
As you can see, "colour" (beam of light) reflected by any object depends on the structure of the atoms and molecules it consists of.
by Aziz Shahhuseynov, special thanks to Marieke and Lyubov