Black hair is the darkest and most common of all human hair colors globally, due to larger populations with this dominant trait. It is a dominant genetic trait, and it is found in people of all backgrounds and ethnicities. It has large amounts of eumelanin and is less dense than other hair colors. In English, black hair is sometimes described as soft-black, raven black, or jet-black. The range of skin colors associated with black hair is vast, ranging from the palest of light skin tones to dark skin. Black-haired humans can have dark or light eyes.
This is found in its greatest distribution in Asia, pre-Columbian Americas and Africa. Black hair is also particularly common in people of Asia, Eastern Europe, Latin America, Southern Europe and Africa regardless of ethnolinguistic affiliation. For example, although brown hair is the dominant type some Southern Europeans are particularly noted for their straight or wavy black hair, and it can be combined with either dark (such as brown) or light (such as green, gray or blue) colored eyes. Irish people with these traits are sometimes known as the "Black Irish". Though this characteristic can be seen in people throughout the United Kingdom and Northwestern Europe, it becomes more common in Eastern Europe.
Dark haired people, ranging from dark chestnut and deep brown to black, with either dark or light colored eyes, can also be seen among the Indo-European and non-Indo-European ethnic groups in Iran, the Caucasus, Central Asia, Afghanistan and India. Hair is naturally reflective, so black hair isn't completely dark in bright light. However, the darkest shade is deep enough that it doesn't give the reflection a warm, neutral tone. Instead, the sheen can seem almost blue, like the iridescence of a raven's wing. Thus, it's known as raven-black. It's found in people of African, Latin American, South Asian and Southeast Asian descent. Black hair overwhelmingly predominates in almost all parts of Asia, although areas in Northwestern Asia (mainly Turkey, Cyprus, Lebanon, Israel, Georgia, and Armenia) have some non-black haired populations.