Lipids are a group of naturally occurring molecules that includes fats, waxes, monoglycerides, diglycerides, triglycerides, phospholipids, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), and others. The basic biological roles of lipids include energy storage, signaling, and acting as structural components of cell membranes. Lipids have many applications in the cosmetic and food industries as well as in nanotechnology. Lipids are very different in both their individual compositions and functions. These diverse compounds that make up the lipid family are so grouped because they are insoluble in water. They are however soluble in other organic solvents such as ether, acetone, and other lipids. This review is focused on some basic points of lipids such as the difference between docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), the role and function of lipids and their applications in food industry. Moreover, it presents the mechanism of lipids oxidation, and how to measure and prevent the oxidation of lipids.