Glycolic acid is an Alpha-Hydroxy Acid (AHA) which naturally occurs in sugar cane, it has the smallest molecular size of all the AHA's allowing it to better penetrate the skin. It is applied to the skin in various strengths ranging from 20-70% for varying time frames depending on the desired result and skin response. It loosens the thickened surface layers that appear as dry, rough, scaly skin and stimulates the production of collagen in the deeper layers.