This book provides a comprehensive exploration of free radicals in organic chemistry, focusing on their fundamental properties, generation methods, and reactivity patterns. It begins with an introduction to free radicals as reactive intermediates in various chemical reactions. It details the primary methods of generating free radicals, including thermal, photochemical, and electron transfer processes. The book then examines the stability of free radicals, highlighting factors like resonance, hyperconjugation, and inductive effects that influence the behaviour of free radicals. In terms of reactivity, it discusses how free radicals engage in addition, substitution, and elimination reactions. The book delves into their applications in industrial processes, including polymerization, combustion, and material synthesis. The book further explains all various named reactions, coupling reactions and rearrangement reactions that involves free radicals. This book is an essential resource for understanding the role of free radicals in organic chemistry, both as fundamental intermediates and as key players in various chemical, biological, and environmental processes.