Tattooes are permanent ink drawings or markings inserted under the skin (usually for a decorative purpose). This type of practice on humans is part of body modification, along with piercing, branding, scarification...
Human skin is composed of three layers : epidermis, dermis and hypodermis and the ink is inserted in a rather precise depth (between the epidermis and the dermis) from 1 to 4 mm.

The word tattoo comes from Tahitian and means “drawing” or “marking”. The root of the word “ta” means “hit” or “make an incision”. “Tatoo” was a term coined by Doctor Berchon, a translator enrolled in Cook's journey to Tahiti in 1722.

Tattooing is a practice which origin can be traced back to Neolithic (Ötzi, the frozen man found in the italo-austrian Alps had tattoos (probably for therapeutic purposes). It is not very well considered in Western culture, probably due to Judeo-Christian condemnation related to it (Old Testament)

There are a variety of reasons why people get tattoos : religion, decoration, identification to a particular group etc...It is also a way to express ones uniqueness or to provoke. Nowadays tattoos are perform with a machine called “dermograph”, which makes needles go up and down at a rather fast speed thus inserting the ink forming the tattoo.

The Guinness World Record of the longest tattoo session was performed by artist Wade Darby on 10 people (5 hours each) for a total of 50 hours non-stop tattooing!