Ceramides are a family of waxy lipid molecules. A ceramideis composed of sphingosine and a fatty acid. Ceramides are found in high concentrations within the cell membrane of cells. They are one of the component lipids that make up sphingomyelin, one of the major lipids in the lipid bilayer. Contrary to previous assumptions that ceramides and other sphingolipids found in cell membrane were purely structural elements, ceramide can participate in a variety of cellular signaling: examples include regulating differentiation, proliferation, and programmed cell death (PCD) of cells.

Ceramides are lipids that help form the skin's barrier and help skin retain moisture. Ceramides also help the skin protect against environmental aggressors like irritants, and pollution. Without the proper ratio of ceramides, the skin's barrier can become compromised, leading to dryness, itching and irritation.