Modifications
Modifications are the choices that shape how your doll looks. Skin tone, eyes, eyebrows, eyelashes, the colour and size of the areolas, the shade of the intimate area, the manicure and pedicure, and the internal textures.
Almost all of them are set permanently at the production stage, and most of them are free. That combination is what makes them worth understanding properly before you order: they cost you nothing but a decision, and you can't change your mind afterwards.
Modifications are separate from options. A modification changes how the doll looks; an option changes how she is built (skeleton, head type, heating, and so on). The two are ordered in the same customisation section but behave very differently.
The available modifications differ between silicone and TPE dolls, so they're documented separately below.