The article provides an overview of the role of peroxisome proliferator-activated receptor alpha (PPARα) in various biological processes, particularly in lipid metabolism and other pathways. PPARα is a ligand-activated transcription factor that regulates a wide range of processes, including inflammation, immunity, nutrient metabolism, and energy homeostasis. It serves as a molecular target for hypolipidemic fibrates drugs and is activated by numerous fatty acids and fatty acid-derived compounds. The article highlights the involvement of PPARα in liver-specific gene regulation, emphasizing its role in fatty acid oxidation, lipogenesis, lipoprotein metabolism, glucose/glycerol metabolism, cholesterol/bile metabolism, amino acid metabolism, and inflammation. It also discusses the tissue expression profile, structure, ligands, and target genes of PPARα in both mouse and human. The authors present a detailed analysis of PPARα target genes, focusing on hepatic lipid metabolism and other biological processes, and discuss the differences between mouse and human. The article concludes by reflecting on the 20th anniversary of PPARα's discovery and the ongoing challenges in understanding its molecular mechanisms and functional consequences.The article provides an overview of the role of peroxisome proliferator-activated receptor alpha (PPARα) in various biological processes, particularly in lipid metabolism and other pathways. PPARα is a ligand-activated transcription factor that regulates a wide range of processes, including inflammation, immunity, nutrient metabolism, and energy homeostasis. It serves as a molecular target for hypolipidemic fibrates drugs and is activated by numerous fatty acids and fatty acid-derived compounds. The article highlights the involvement of PPARα in liver-specific gene regulation, emphasizing its role in fatty acid oxidation, lipogenesis, lipoprotein metabolism, glucose/glycerol metabolism, cholesterol/bile metabolism, amino acid metabolism, and inflammation. It also discusses the tissue expression profile, structure, ligands, and target genes of PPARα in both mouse and human. The authors present a detailed analysis of PPARα target genes, focusing on hepatic lipid metabolism and other biological processes, and discuss the differences between mouse and human. The article concludes by reflecting on the 20th anniversary of PPARα's discovery and the ongoing challenges in understanding its molecular mechanisms and functional consequences.