Acids are great because they exfoliate away dull, dead skin and gently remove discolourations over time. AHAs (alpha-hydroxy acids) target the surface layers of the skin, while BHAs (beta-hydroxy acids) also unclog pores. Kojic acid is used as a skin lightening agent because of its effects on a protein known as tyrosinase. Melanin is the primary pigment in skin. Thus, by inhibiting the tyrosinase protein's ability to make melanin, kojic acid is able to prevent skin pigmentation, which can help lighten the skin's tone.