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.

While tattoos are considered permanent, it is possible to remove them. Complete removal, however, may not be possible (although many doctors and laser practitioners make the claim that upwards of 95% removal is possible with the newest lasers, especially with black and darker colored inks), and the expense and pain of removing them typically will be greater than the expense and pain of applying them. Some jurisdictions will pay for the voluntary removal of gang tattoos.

Tattoo removal is most commonly performed using lasers that react with the ink in the tattoo, and break it down. The broken-down ink is then absorbed by the body, mimicking the natural fading that time or sun exposure would create. This technique often requires many repeated visits to remove even a small tattoo, and may result in permanent scarring. The newer Q-switched lasers are said by the National Institute of Health to result in scarring only rarely, however, and are usually used only after a topical anesthetic has been applied. The NIH recognizes five types of tattoo; amateur, professional, cosmetic, medical, and traumatic (or natural). Amateur tattoos are easier and quicker to remove, usually, than professional tattoos. Areas with thin skin will be more likely to scar than thicker-skinned areas. There are several types of Q-switched lasers, and each is effective at removing a different range of the color spectrum. This laser effectively removes black, blue, purple and red tattoo pigment. New lasers like the Versapulse & Medlite laser treat these colors & yellow and green ink pigment, typically the hardest colors to remove. Black is the easiest color to remove.