If human skin comes and goes like dust in the wind, why do tattoos stick around? The explanation is simple. The top layer of skin is called the epidermis. This page from A Moment of Science explains that while the epidermis is always regenerating, a tattoo needle actually penetrates through to the dermis, the second level of skin. It’s here that the tattoo makes its home for the rest of your natural life.
Of course, you can get rid of a tattoo in many ways, but none are as cheap or painless as avoidance. So unless you’re sure you want a Chinese character, a giant eagle, or (God help you) a tribal band tattooed around your upper arm for all eternity, it’s probably best to stick to the Cracker Jack variety.