Research in the area of porphyrins, phthalocyanines and related macrocycles continues to expand at a phenomenal rate with literally thousands of original articles being published every year in the fields of chemistry, physics, biology, material science and photodynamic therapy. The current volume comprehensively summarizes key aspects involved in the synthesis, characterization and use of these compounds, as well as computational methodologies for the design of novel tetrapyrroles whose structural and electronic properties are described. Each chapter is authored by an expert or group of experts in the field who were asked to write 'a review for the ages' and we anticipate that what is written in this volume will remain relevant for at least the next 15 years, and possibly longer.This volume should be considered as required reading for both new and experienced researchers in a number of sub-disciplines where tetrapyrroles are studied or utilized in a variety of applications. A complete understanding of the chemistry of these compounds necessitates not only a knowledge of what has been accomplished in the area of synthesis and characterization but also a knowledge of what is possible in the future when using porphyrins and related tetrapyrroles as key components for applications in catalysis, energy production and biomedical applications.