Lipids are a broad group of organic compounds that include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids, and others. They are essential to many body functions and serve as the building blocks for all living cells. Lipids are hydrophobic or amphiphilic small molecules, and their amphiphilic nature allows them to form structures such as vesicles, multilamellar/unilamellar liposomes, or membranes in an aqueous environment. Lipids are made up of oxygen, carbon, and hydrogen, which bond to each other to form different types of lipids.

Lipids have several functions in the body, including storing energy, signaling, and acting as structural components of cell membranes. They are also involved in the absorption of fat-soluble vitamins and the production of hormones. Lipids are classified into eight categories: fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterol lipids, prenol lipids, saccharolipids, and polyketides.

Although the term "lipid" is sometimes used as a synonym for fats, fats are a subgroup of lipids called triglycerides. Lipids also encompass molecules such as fatty acids and their derivatives (including tri-, di-, monoglycerides, and phospholipids), as well as other sterol-containing metabolites such as cholesterol.

Lipids play an important role in the body, but producing the wrong amount of lipids can cause conditions such as hyperlipidemia (high lipid levels) or hypolipidemia (low lipid levels) . A lipid panel or lipid profile can tell a healthcare provider if a person is at risk for cardiovascular disease.

In summary, lipids are a diverse group of organic compounds that are essential to many body functions. They include fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, phospholipids, and others. Lipids are hydrophobic or amphiphilic small molecules that play a crucial role in storing energy, signaling, and acting as structural components of cell membranes.