Book excerpt: Porphyrins, phthalocyanines and their numerous analogs and derivatives are materials of tremendous importance in chemistry, materials science, physics, biology and medicine. They comprise the red color in blood (heme) and the green in leaves (chlorophyll); they are also excellent ligands that can coordinate with almost every metal in the Periodic Table. Grounded in natural systems, porphyrins are incredibly versatile and can be modified in many ways; each new modification yields derivatives demonstrating new chemistry, physics and biology, with a vast array of medicinal and technical applications.Because porphyrins are currently employed as platforms for study of theoretical principles and applications in a wide variety of fields, the Handbook of Porphyrin Science represents a timely ongoing series dealing in detail with the synthesis, chemistry, physicochemical and medical properties and applications of polypyrrole macrocycles. It is noteworthy that every year, new applications for tetrapyrrole ligands are developed and exploited.Professors Karl Kadish, Kevin Smith and Roger Guilard are internationally recognized experts in the research field of porphyrinoids, each having his own separate but complementary area of expertise in the field. Between them, they have published over 1750 peer-reviewed papers and jointly edited more than 55 books on diverse topics related to porphyrins and phthalocyanines. In assembling the set of new volumes of this unique handbook, they have selected and attracted the very best scientists in each sub-discipline as contributing authors.The Handbook of Porphyrin Science will prove to be a modern authoritative treatise on the subject as it continues as a collection of up-to-date works by world-renowned experts in the field. Complete with hundreds of figures, tables and structural formulas, and thousands of literature citations, all researchers and graduate students in this field will find it to be an essential, major reference source now, and for many years to come.