Produced by bacteria, fungi and plants, siderophores are low-molecular-weight chelating agents (200-2,000 Da) to facilitate uptake of iron (Fe). They play an important role in extracellular Fe solubilization from minerals to make it available to microorganisms. Siderophores have various chemical structures and form a family of at least 500 different compounds. Some antibiotics (i.e., albomycins, ferrimycins, danomycins, salmycins, and tetracyclines) can bind Fe and some siderophores showed diverse biological activities. Functions and applications of siderophores derived from actinobacteria were reviewed to better understand the diverse metabolites.