Wavelengths are reflected off an object, and the human eye recognizes these wavelengths as color. When an individual sees the color black, he is seeing an object that absorbs all of the wavelengths of color, and reflects almost none.
This creates an absence of color that the human eye recognizes as the color black. Objects that reflect no light at all are invisible to the human eye. Lightness and darkness are processed separately from color wavelengths, which explains why the color black has shades of darkness and lightness. The color white is the opposite of black. White reflects all colors and absorbs almost none.