Colours can appear in three ways: as "light source colour," as "reflected colour," and as "filtered colour."

Light source colour

The term "light source colour" refers to the colour of light emitted by an object, such as the sun or a fluorescent lamp. The colours we see are determined by the constituent wavelengths contained in the light from the object.

Reflected colour

"Reflected colour" is colour we perceive when light of the corresponding wavelength is reflected off of an object other than the light source. The colours we see are determined by the range of wavelengths that are reflected off the object and the range of wavelengths that are absorbed by it. An object that absorbs all wavelengths of light in the visible spectrum appears black, and one that reflects all of them appears white.

Filtered colour

The term "filtered colour" refers to colour we see after light has passed through an object. The colour of the object is determined by the range of wavelengths that pass through it and the range of wavelengths that are absorbed by it. Traffic lights provide an example of filtered colour.