A must have, this gives your skin amazing moisture, Hyaluronic Acid (which you might find hiding on the labels of some of your skincare products as HA), is naturally occurring in the human body. The substance works as a magnet for moisture, helping your cells retain as much of it as possible so that your skin feels and appears hydrated, plump and healthy.
Now for the science-y bit. Just a single gram of hyaluronic acid has the impressive ability to hold up to six (yep, six) litres of water. Add to that, a super smart ability to regulate that moisture within the cells, so as not to drown them and you've got one genius ingredient.