Ascorbic Acid is a naturally occurring organic compound with antioxidant properties. It is a white solid, but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. Because it is derived from glucose, many animals are able to produce it, but humans require it as part of their nutrition. Other vertebrates which lack the ability to produce ascorbic acid include other primates, guinea pigs, teleost fishes, bats, and some birds, all of which require it as a dietary micronutrient (that is, in vitamin form). There exists a D-ascorbic acid, which does not occur in nature. It may be synthesized artificially. It has identical antioxidant properties to L-ascorbic acid yet has far less vitamin C activity (although not quite zero).