Bile acids, synthesized endogenously from cholesterol, play a central role in metabolic regulation within the enterohepatic circulatory system. Traditionally known as emulsifying agents that facilitate the intestinal absorption of vitamins and lipids, recent research reveals their function as multifaceted signal modulators involved in various physiological processes. These molecules are now recognized as key regulators of chronic metabolic diseases and immune dysfunction. Despite progress in understanding their roles, their structural diversity and the specific functions of individual bile acids remain underexplored.