Book excerpt: Phosphorus-Nitrogen Compounds: Cyclic, Linear, and High Polymeric Systems concerns itself with the chemistry of compounds containing alternating phosphorus - nitrogen atoms in the skeleton. The monograph aims to be an introduction to phosphorus-nitrogen chemistry, a review of advances in the field, and reference work. The text is divided into three parts. Part I covers the introduction, historical background, and nomenclature of phosphorus-nitrogen compounds and the theories in bonding and structure of phosphazenes and phosphazanes. Part II deals with reactions such as the synthesis of the phosphorus-nitrogen skeleton, hydrolysis of phosphazenes and phosphazanes, and the aminolysis of halophosphazenes. Part III discusses polymer chemistry and includes topics such as polymerization, depolymerization, and phosphazene polymers. The book is recommended for students and practitioners in the field of chemistry, especially those concerned with phosphorus nitrogen compounds and polymeric systems.