Kojic acid comes from fungi and can also be from fermented foods. It helps even out skin tone and reduce hyperpigmentation.

This ingredient works by blocking tyrosine, an enzyme that starts the process of skin darkening.

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.