So the selective absorption of light by a particular material occurs because the frequency of the light wave matches the frequency at which electrons in the atoms of that material vibrate. Absorption depends on the state of an object's electron.

Why is light reflected or absorbed?

Reflection and transmission of light waves occur because the frequencies of the light waves do not match the natural frequencies of vibration of the objects. When light waves of these frequencies strike an object, the electrons in the atoms of the object begin vibrating.

Is light always absorbed?

In most cases not all the light is absorbed by the surface and the light that is not absorbed is scattered. We also find that the light that is absorbed has a particular wavelength dependant on the nature of the surface, ie what material it is and what dyes might have been added to it.