Brown hair

Brown hair is the second most common human hair color, after black hair. It varies from light brown to almost black hair. It is characterized by higher levels of the dark pigment eumelanin and lower levels of the pale pigment pheomelanin. Its strands are thicker than those of fair hair but not as much as those of red hair. People with brown or black hair are often referred to as brunette, which in French is the feminine form of brunet, which is the diminutive of brun (brown, brown-haired or dark-haired).

Brown hair is common among populations in Western world, especially among those from Central Europe, Southern Europe, United States and also some populations in Greater Middle East where it transitions smoothly into black hair. Brown hair is common among Australian Aborigines and Melanesians.

https://en.wikipedia.org/wiki/Brown_hair