Book excerpt: Focusing on new biophysical and analytical methods that can assess lipid status and the improvement of skin condition, this reference provides essential quantitative information on the interaction of topically applied lipids with skin barrier lipids. Containing contributions from internationally recognized specialists and over 1000 references, drawings, photographs, and tables, it explores how different lipid varieties function in cosmetic formulations and on the skin. Coverage includes the chemistry, structure, and biological functions of skin lipids and their interaction with the lipids formulated into skin and hair care preparations.