Phospholipids

Occur naturally in skin and can be derived from plant and animal sources

Are hygroscopic, meaning they attract water from surrounding air and hold it where hydration is needed

Have antioxidant properties

Can help deliver other ingredients more effectively to skin

Phospholipids are types of lipids (fats) composed of glycerol, fatty acids, and phosphate (a salt made from the non-metallic element phosphorus). They occur naturally within the human body and can be derived from plant and animal sources, such as soybeans, egg yolks, and milk. Phospholipids can also be synthetically derived. Lecithin is an example of a phospholipid.
Phospholipids in skin care have value for numerous reasons– chief among them is that they are hygroscopic, meaning they pull in water from surrounding air and hold it where more hydration is needed. That means they have excellent moisturizing capabilities without being occlusive.
Applying phospholipids to skin can help replace phospholipids that are depleted either through cleansing or from environmental factors. Research also shows that phospholipids can have antioxidant properties and be effective in helping deliver other ingredients more effective to skin in cosmetics.
As skin-natural ingredients, phospholipids are considered safe as used in skin care in concentrations up to 50%; however, they are most often used as part of a blend with glycerin, lecithin (itself a source of phospholipids as stated above) and ceramides.

See: Phospholipid