Natural products originate as secondary metabolites from a myriad of sources, including terrestrial plants, animals, marine organisms, microorganisms, terrestrial vertebrates and invertebrates. The book is focused on the identification and characterization of natural key compounds that control biologically and physiologically intriguing phenomena. The discovery of new bioactive molecules, facilitated by a deeper understanding of nature, should advance our knowledge of biological processes and lead to new strategies to treat disease. This book is aimed to summarize the chemistry and biological activities and applications of a variety of natural products and biologics and review the microbial systems used to produce these pharmaceutical compounds.