This is often confused with Vitamin C Ester, or ascorbyl palmitate, which is a man-made, in other words not found
in nature, fat
soluble form of Vitamin C that is often found
in skin products because it doesn't oxidize as quickly on contact with air. Natural Vitamin C is water soluble, as is Ester-C, which again is just a trademark. Lots of companies make the exact equivalent of Ester-C but just call it buffered Vitamin C.