Toner is a very important product as it adds moisture to the face. Hydration is very important for the skin, even if you have oily skin. Not only does a toner hydrate the skin, but it also balances the skin's pH. The pH balance can be knocked off by masks and exfoliators, which is why it is very important to use a toner afterwards. A high pH can cause irritation, redness, and acne, while a high pH can cause dryness and flaking of the skin. The normal pH level is five, and that number will change as you are doing your routine. Balance is everything in the skincare world.
Toners help the skin absorb the other products that will be applied throughout the routine. It is because toners are moisturizers, that they allow the skin to really absorb the other products.