Tattoos are, simply put, drawing on our skin. Some of them fade right away, if they drawn on the surface of the skin, or others stay permanently, if they were created in the dermis, the layer that is deeper in the skin.
The skis has several layers: epidermis, dermis and subcutis or hypodermis. The permanent tattoos are inserted in the dermis via needles that push dye dozens of times per minute. That dye remains in there for as long time, even if macrophages a type of white cells (leucocytes) that is meant to eat whatever intruder it sees, eat up part of that dye.
Since the skin is transparent, the dye that remains in the dermis will be seen for many years to come. It will fade away with time, but it will still be there and only laser procedures will be able to break down the dye pockets and make them vanish due to the action of macrophages.
What do you think about tattoos? Are they taboos?