Chromophore

A chromophore is the part of a molecule responsible for its colour.
The colour is caused when a molecule absorbs certain wavelengths of visible light. It transmits or reflects only other wavelengths, which causes the colour we see.
In biological molecules that capture or detect light energy, the chromophore is the part of the molecule which responds when hit by light.
Chromophores make the colour in chromatophores, which are the pigment-containing and light-reflecting cells found in many animals.