A tattoo is a marking made by inserting indelible ink into the dermis layer of the skin to change the pigment. Tattoos on humans are a type of decorative body modification, while tattoos on animals are most commonly used for identification purposes. The first written reference to the word, "tattoo" (or Samoan "Tatau") appears in the journal of Joseph Banks, the naturalist aboard Captain Cook's ship the HMS Endeavour in 1769: "I shall now mention the way they mark themselves indelibly, each of them is so marked by their humor or disposition".

Tattooing has been practiced for centuries worldwide. The Ainu, the indigenous people of Japan, traditionally had facial tattoos. Today one can find Berbers of Tamazgha (North Africa), Māori of New Zealand, Hausa people of Northern Nigeria, Arabic people in East-Turkey and Atayal of Taiwan with facial tattoos. Tattooing was widespread among Polynesian peoples and among certain tribal groups in the Taiwan, Philippines, Borneo, Mentawai Islands, Africa, North America, South America, Mesoamerica, Europe, Japan, Cambodia, New Zealand and Micronesia. Despite some taboos surrounding tattooing, the art continues to be popular in many parts of the world.