This book presents comprehensive accounts of the chemistry revolving around the sulphonamides. Sulfonamides are widely present in various drugs as a functional group and are a manmade synthetic drug. Hence, their extended research is a prerequisite for every practitioner of organic chemistry. Chapter 1 introduces the synthesis, reactivity, acidity, and pharmaceutical properties of the sulphonamides. It highlights the synthesis of biologically active sulphonamides, the study of their biological activity by QSAR method, and their medical applications. Chapter 2 deals with the classification of sulphonamides (i.e. acyclic and cyclic) and their structural activity relationship. It also describes the application of sulphonamides in pharmaceuticals as antimicrobial, anti-diabetic, anti-viral, anti-cancer, anti-inflammatory and anti-malarial agents. Chapter 3 reviews the synthetic attempts towards sulphonamide synthesis by employing the fixation of sulphur-dioxides. These approaches have been categorized into three parts: a) transition metal-catalyzed, b) employing Lewis acid, c) photocatalytic. Chapter 4 discusses the use of sulphonamides as potent organocatalysts, briefly describing how the mono- and C2-symmetric bis-sulfonamides act as efficient bifunctional and multifunctional organocatalysts in the enantioselective Michael addition of carbonyl compounds to α,β-unsaturated compounds. Chapter 5 details the oxidative sulphonamidation of alkenes and dienes, which also direct the routes to the synthesis of numerous heterocycles and linear compounds. Special emphasis is given to the comparison of reactivity of triflamides, arenesulfonamides, and the deprotection of sulfonamides. Chapter 6 describes the therapeutic properties of sulphonamides, which are significantly increased by the presence of the metal ions and ligands. This complex generation provides the opportunity to exploit the unique properties of metal centers, such as multiple oxidation states, redox properties, a wide variety of coordination numbers, symmetries and structural patterns, which offer highly adaptable platforms for drug design. Chapter 7 provides an overview of the clinical applications of sulphonamides on the toxicity and pharmacokinetic aspects of various sulpha-drugs. The mechanism involved in the development of sulfonamide resistance is briefly discussed. Thus, this book summarizes important attempts undertaken by chemists and biologists worldwide in the area of sulphonamides. Most importantly, the book also correlates the structural activity relationship and the related biological activity of the sulphonamides, attracting both novice and experienced chemists across the globe.