This lecture covers the structure and function of sphingolipids, which are composed of a long-chain base called sphingosine. It explains the subclasses of sphingolipids, such as sphingomyelins, neutral glycosphingolipids, and gangliosides, and their roles in cell membranes. The lecture also discusses glycosphingolipids as receptors for toxins and viruses, blood group antigens, and inborn errors of glycosphingolipid metabolism.