Hyaluronic acid is ?

a substance produced in the body and are mostly in skin layer.

support skin substances such as collagen, elastin, and fibrous tissue.

the most important factor in skin moisturizing.

increases firmness of skin, and supply nutrition to tissue cells.

Hyaluronic acid has outstanding moisturizing power as it is called "moisture storage tank", and perform as a useful natural moisture provider in the body. If hyaluronic acid is produced insufficiently, the skin becomes like a dry sponge that lacks the ability to absorb moisture.