Lipid droplets (LDs) are intracellular organelles found in most cells, playing crucial roles in metabolism and energy storage. Recent studies have highlighted the importance of emulsion principles in understanding LD biology. LDs function as oil-in-water emulsions within the aqueous cytosol, storing neutral lipids like triacylglycerols (TG) and sterol esters (SE). The unique architecture of LDs requires specialized mechanisms for formation, growth, and shrinkage, which enable cells to control the use of emulsified oil. The composition of phospholipid surfactants at the LD surface is critical for growth and catabolism, and it also influences protein targeting to LDs. This review emphasizes the biophysical and emulsion science concepts relevant to LD biology, including the role of surfactants, protein targeting, and the mechanisms of LD formation, growth, and disappearance. The review also discusses non-canonical functions of LDs, such as protein storage and viral assembly, and highlights the integration of soft matter physics into the field of LD research.Lipid droplets (LDs) are intracellular organelles found in most cells, playing crucial roles in metabolism and energy storage. Recent studies have highlighted the importance of emulsion principles in understanding LD biology. LDs function as oil-in-water emulsions within the aqueous cytosol, storing neutral lipids like triacylglycerols (TG) and sterol esters (SE). The unique architecture of LDs requires specialized mechanisms for formation, growth, and shrinkage, which enable cells to control the use of emulsified oil. The composition of phospholipid surfactants at the LD surface is critical for growth and catabolism, and it also influences protein targeting to LDs. This review emphasizes the biophysical and emulsion science concepts relevant to LD biology, including the role of surfactants, protein targeting, and the mechanisms of LD formation, growth, and disappearance. The review also discusses non-canonical functions of LDs, such as protein storage and viral assembly, and highlights the integration of soft matter physics into the field of LD research.