4-Amino-N-(4-aminophenyl)benzenesulfonamide, also known as 4,4'-diaminodiphenylsulfone (DDS) or Dapsone, is primarily used as a latent curing agent for epoxy resins in high-performance applications including aerospace composites, structural laminates, adhesives, and electronic encapsulants, valued for its high melting point, thermal stability, and controlled reactivity. It also serves as an intermediate in the synthesis of azo dyes for the textile industry, contributing to dyes with excellent colorfastness and durability. In pharmaceuticals, it is employed as an antibacterial agent (under the name Dapsone) for treating leprosy, dermatitis herpetiformis, and as prophylaxis for Pneumocystis pneumonia, due to its sulfonamide group's antimicrobial properties. Additionally, in research, it acts as a building block for complex organic molecules. This versatility underscores its importance as a specialty chemical in polymer, dye, pharmaceutical, and medicinal chemistry industries.