Lipid
![Structures of some common lipids. At the top are cholesterol[1] and oleic acid.[2] The middle structure is a triglyceride composed of oleoyl, stearoyl, and palmitoyl chains attached to a glycerol backbone. At the bottom is the common phospholipid, phosphatidylcholine.[3]](/uploads/202501/15/Common_lipids_lmaps4645.png)
![Structure of the saccharolipid Kdo2-lipid A.[42] Glucosamine residues in blue, Kdo residues in red, acyl chains in black and phosphate groups in green.](/uploads/202501/15/Kdo2-lipidA4645.png)
Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids, and others. The main biological functions of lipids include storing energy, signaling, and acting as structural components of cell membranes. Lipids have applications in the cosmetic and food industries as well as in nanotechnology.