Black is, by definition, the absence of color. Color is determined when the human eye absorbs the wavelengths of visible light, and an object that is truly black is an object that does not reflect light, so there is no light for the eyes to interpret.
That said, when it comes to creating black pigments, paints or inks, black is created by mixing equal parts of the three primary colors: red, yellow and blue. Variations in these mixtures create different shades of gray, but only true black resists reflecting light. It is difficult to achieve a pigment that truly does not reflect light.