Phospholipids are a major class of amphiphilic lipids consisting of a glycerol backbone esterified with two fatty acid chains and a phosphate group attached to a polar head (e.g., choline in phosphatidylcholine). They are essential components of cell membranes, forming lipid bilayers due to their hydrophilic head and hydrophobic tails. In food science, they act as emulsifiers (e.g., lecithin from soy or egg yolk), stabilizing mixtures of oil and water. They exhibit low volatility and are stable under typical cooking conditions. Chemically, they participate in signaling pathways and are precursors to other bioactive molecules. Their properties vary with fatty acid composition and head group, influencing melting points and phase behavior in aqueous environments.