Niacinamide is a type of Vitamin B3, found naturally in certain foods. It sports restorative anti-inflammatory actions that can help treat acne, and does a whole heap of other stuff like balancing skin tone, hydrating effectively, and strengthening the skin’s surface to fight fine lines. It is most commonly applied topically via serums and acne solutions, but can also be taken as a dietary supplement. The Ordinary’s Niacinamide 10% + Zinc 1%  is one place you can find it.