Siderophores are a class of small molecules renowned for their high iron binding capacity, essential for all life forms requiring iron. This article provides a detailed review of the diverse classifications, and biosynthetic pathways of siderophores, with a particular emphasis on siderophores synthesized via nonribosomal peptide synthetase (NRPS) and non-NRPS pathways. We further explore the secretion mechanisms of siderophores in microbes and plants, and their role in regulating bioavailable iron levels. Beyond biological functions, the applications of siderophores in medicine, agriculture, and environmental sciences are extensively discussed. These applications include biological pest control, disease treatment, ecological pollution remediation, and heavy metal ion removal. Through a comprehensive analysis of the chemical properties and biological activities of siderophores, this paper demonstrates their wide prospects in scientific research and practical applications, while also highlighting current research gaps and potential future directions.