Here's why:
* Epidermis (Outer layer): This layer is constantly shedding, so ink injected here would quickly disappear.
* Dermis (Middle layer): This layer is much thicker and contains collagen fibers, which hold the ink in place. It's also less prone to shedding compared to the epidermis.
* Hypodermis (Inner layer): This layer is mostly fat and connective tissue. Ink injected here could migrate and create uneven lines.
So, the dermis is the ideal location for tattoo ink to stay in place and create the desired design.