What is Hydration vs Moisture?

Hydration = water content in skin. Addressed by humectants (hyaluronic acid, glycerin, panthenol) that bind water. Moisture = lipid content. Addressed by emollients (squalane, oils) and occlusives (petrolatum, ceramide creams) that fill gaps and seal in water. Dehydrated skin needs humectants; dry skin needs emollients + occlusives. Many people have dehydrated OILY skin, which needs humectants without heavy lipids — gel moisturizers over creams.