The space behind the ear is small and curved, running along the back of the ear toward the neck. It suits tiny, simple designs that follow that curve: a crescent moon, a feather, a sprig of leaves, a few stars, or a symbol with personal meaning. Designs that trail downward can later connect into a neck piece.
The skin here is thin and sits over bone, and it is rubbed by glasses, masks and phones. Very fine lines and tiny text can soften or spread with time, so slightly heavier lines and simple shapes hold up better. It sees less sun than the front of the neck, which helps.
Visibility depends on your hair. Long hair worn down covers it completely, while short hair or an updo shows it to anyone standing beside you. That flexibility makes it a gentler choice than the side of the neck for people who need to stay covered at work.
Healing is usually quick for such small pieces, but the spot is easy to bump. Keep glasses arms and phone screens off it where you can, keep shampoo and hair products away from the fresh tattoo, and try to sleep on the other side for the first nights.