AHA: Alpha Hydroxy Acids are water-soluble acids that help peel away the surface of your skin to promote even skin tone and texture. Common forms of AHA are glycolic acid and lactic acid.
BHA: Beta Hydroxy Acids dive deep into the pores to remove dead skin cells and excess sebum. Common forms of BHA include salicylic acid and citric acid.
PHA: Poly Hydroxy Acids are beneficial for sensitive skin that is prone to redness and irritation from pollutants and harsh chemicals etc. These mild acids are perfect for all skin types, even those with skin conditions such as eczema or rosacea.
(Never ever forget sunscreen!)