Hair color is measured in two ways: by the level and the shade. Color level runs on a scale of one to 10, with one being the darkest color (jet-black) and 10 being the lightest color (platinum blonde).
Within each of those levels are the color pigments-eumelanin (black-brown) and pheomelanin (red-brown), which control the shade of the hair. Dark hair (levels 1-4) contains many red pigments, and blonde hair (levels 7-10) consists mainly of golden pigments.
If your hair shade is somewhere in the middle (levels 5-6), you’re going to have more orange pigments, a combination of red and yellow.
