What are these raised tattoos you see on pro athletes?

Answer 1

A tattoo is, by its very nature, a scar. The trick is to do as little damage to the skin as possible while applying the tattoo, so that the scar tissue that forms is minimal (sufficient to retain the pigment forever, yet not so significant as to cause a three-dimensional scar). When a tattooer "hammers" an area, it damages the skin sufficiently to cause 3D scarring. IT's a matter of training, knowledge of equipment, knowledge of skin, etc. There's also customers who habitually keloid (3D scarring- people of African descent tend to keloid, which is why some scarification practices of great beauty evolved in the African continent).