Derma rollers have a number of uses, but the main ones are for improving pigmentation issues and improving the surface of the skin.
Fine lines, acne scars, and hyperpigmentation are all said to be diminished with regular derma rolling.

When the dermaroller is rolled over the skin, the small, fine needles on the roller puncture the skin.
The holes that the needles create in the skin are tiny and considered to be superficial. For this reason, the treatment is not seen as invasive.
When the skin is punctured, this creates a controlled skin injury. It does not cause actual damage to the outer layer of skin. The needles help to break down any scar tissue.