Colour is defined as the attribute of things that is caused from the light they reflect, transmit, or emit in so far as this light causes a visual sensation that depends on its wavelengths
To see colour, you must have light. When light shines on an object some colours bounce off the object and others are absorbed by it. Our eyes only see the colours that are bounced off or reflected. Colour is simply the range of visible light that humans can see. Light is made of electromagnetic waves. These waves spread out from any light source, such as the sun. Different colours have different wavelengths, which is the distance between corresponding parts of two of the waves. The human eye is capable of seeing only light with wavelengths between 380 and 750 nanometers. For example, the visible spectrum begins with the wavelengths that we call violet, between 380 and 450 nm, then moves on to blue, green, yellow, and orange, and ends with what we call red, between 590 and 750 nm.
The trouble in this scientific approach is that some colors considered important such as black and white, as well as colors like pink, don’t seem to have a place in a visible spectrum of light that goes only from violet to red. So does this mean that black and white aren’t real colors?
It depends on how you want to define colour. If colour is solely the way physics describes it, the visible spectrum of light waves, then black and white are outcasts and don’t count as true, physical colours. Colours like white and pink are not present in the spectrum because they are the result of our eyes’ mixing wavelengths of light. White is what we see when all wavelengths of light are reflected off an object, while pink is a mix of the red and violet wavelengths. Black, on the other hand, is what our eyes see in a space that reflects very little light at all. That’s why, if you enter a room with the lights turned off, everything is dark and black. If you include in the definition of colour, however, all of the ways in which human eyes process light and the lack of it, then black and white, as well as pink, Can in fact be considered rightfully a colour.