Purpose

Human history shows that tattoos have served in many diverse cultures as rites of passage, marks of status and rank, symbols of religious and spiritual devotion, decorations for bravery, sexual lures and marks of fertility, pledges of love, punishment, amulets and talismans, protection, and as the marks of outcasts, slaves and convicts.

Today, people choose to be tattooed for cosmetic, religious and magical reasons, as well as a symbol of belonging to or identification with particular groups (see Criminal tattoos). Some Māori still choose to wear intricate moko on their faces. People have also been forcibly tattooed for a variety of reasons. The best known is the ka-tzetnik identification system for Jews in part of the concentration camps during the Holocaust.

European sailors were known to tattoo the crucifixion on their backs to prevent flogging as a punishment as at that time it was a crime to deface an image of Christ.

Tattoos are also placed on animals, though very rarely for decorative reasons. Pets, show animals, thoroughbred horses and livestock are sometimes tattooed with identification marks, and certain of their body parts (for example, noses) have also been tattooed to prevent sunburn. Such tattoos are performed by veterinarians and the animals are anaesthetized to prevent pain. (Branding would not be considered a tattoo since no ink or dye is inserted).

Procedure:

Some tribal cultures still create tattoos by cutting designs into the skin and rubbing the resulting wound with ink, ashes or other agents. This may be an adjunct to scarification. Some cultures create tattooed marks by "tapping" the ink into the skin using sharpened sticks or animal bones. Traditional Japanese tattoos (irezumi) are still "hand-poked," that is, the ink is inserted beneath the skin using non-electrical, hand-made and hand held tools with needles of sharpened bamboo or steel.

The most common method of tattooing in modern times is the electric tattoo machine. Ink is inserted into the skin via a group of needles that are soldered onto a bar, which is attached to an oscillating unit. The unit rapidly and repeatedly drives the needles in and out of the skin, usually 50 to 3,000 times a minute.

Natural Tattoos

According to George Orwell, workers in coal mines would wind up with characteristic tattoos owing to coal dust getting into wounds. This can also occur with substances like gunpowder. Similarly, a traumatic tattoo occurs when a substance such as asphalt is rubbed into a wound as the result of some kind of accident or trauma. These are particularly difficult to remove as they tend to be spread across several different layers of skin, and scarring or permanent discoloration is almost unavoidable depending on the location. In addition, tattooing of the gingiva from implantation of amalgam particles during dental filling placement and removal is possible and not uncommon.

Temporary Tattoos

Temporary tattoos are a type of body sticker, like a decal. They are generally applied to the skin using water to transfer the design to the surface of the skin. Temporary tattoos are easily removed with soap and water or oil-based creams, and are intended to last a few days.

Other forms of temporary "tattoos" are henna tattoos, also known as Mehndi, and the marks made by the stains of silver nitrate on the skin when exposed to ultraviolet light. Both methods, silver nitrate and henna, can take up to two weeks to fade from the skin.