A tattoo, or dermal pigmentation, is a mark made by inserting pigment into the skin for decorative or other reasons. Tattoos may be made on human or animal skin. Decorative tattoos on humans are a type of body modification, while tattoos on animals are most commonly used for identification or branding.

Tattooing has been practiced worldwide. The Ainu, the indigenous people of Japan, wore facial tattoos. Tattooing was widespread among Polynesian peoples, and among certain tribal groups in the Philippines, Borneo, Africa, North America, South America, Mesoamerica, Europe, Japan, Cambodia and China. Despite some taboos surrounding tattooing, the art continues to be popular all over the world.