Free fatty acids (FFAs) refer to unesterified carboxylic acids with long aliphatic chains, typically containing 4 to 28 carbon atoms, that occur naturally in animal and vegetable fats and oils. Unlike bound fatty acids in triglycerides, FFAs are released through hydrolysis by lipases and contribute to flavor profiles, rancidity, and metabolic processes. They serve as energy sources, signaling molecules, and precursors for eicosanoids. Properties depend on chain length and saturation: short-chain FFAs are volatile with pungent odors, while long-chain saturated ones are solid at room temperature. In food chemistry, FFA content is a quality indicator for oils, with elevated levels signaling degradation. They are generally lipophilic and play roles in digestion and absorption.