What is the pigment that determines hair color?

The pigment that determines hair color is called melanin. There are two main types of melanin: eumelanin, which can be either black or brown, and pheomelanin, which is responsible for red and yellow hues. The combination and concentration of these pigments in the hair follicles contribute to the wide variety of hair colors seen in humans. Genetics play a significant role in determining the type and amount of melanin produced.