Ceramides are a group of lipids made up of a fatty acid and sphingosine. Ceramides are component of sphingomyelin lipids, which is one component of lipid bilayer. Therefore, ceramides are highly abundant in cell membranes. In the past, it is assumed that the sole role of ceramides in the cell membrane is acting as the supporting structural elements. However, this assumption turns out to be false. It is shown that ceramides takes part in a series of physiological process in the body. Here is a related study.