Hair color is generally the pigmentation of hair follicles that is due to two types of melanin: eumelanin and pheomelanin. Generally speaking, if there is more eumelanin present, the color of the hair is darker; if there is less eumelanin that is present, the hair is lighter.
Black hair is the darkest hair color. It has large amounts of eumelanin and compared with other colors, it is less dense than other hair colors. Black hair can range from soft black to blue-black or jet-black.
Brown hair has higher levels of eumelanin but has lower levels of pheomelanin. Brown-haired people are often regarded as brunette.
Blond (or blonde) hair ranges from nearly white (such as platinum blond or tow-haired) to a dark golden blond. It hair can have almost any proportion of pheomelanin and eumelanin, but only in small amounts. More pheomelanin produces a more golden blond color, while more eumelanin creates an ash blond.
Blond hair is most commonly found among Northern and Eastern Europeans and their descendants but can be found elsewhere.
Auburn hair ranges along a spectrum of light to dark red-brown shades. Chestnut hair on the other hand is a reddish shade of brown hair. Chestnut hair is common among the native peoples of Northern, Central, Western, and Eastern Europe.
Red hair has the highest amounts of pheomelanin, around 67%, and usually low levels of eumelanin. It is considered the least common hair color in the world. It is usually found in Scotland and Ireland.