The use of drug substances derived from plants, fungi, bacteria, and marine organisms has a long tradition in medicine. Together with their derivatives, and synthetic compounds deduced from natural product precursors, they represent a major part of today's pharmaceutical market. Within the fast developing discipline of molecular biology, natural products also play an important role as tool compounds in pathway screening and validation of target identification concepts. They provide innovative opportunities in drug discovery, leading to a detailed understanding of biological pathways and revealing the functions of involved enzymes or receptors. This book highlights new trends and aspects in natural products research. It discusses the biodiversity-driven approaches which are now of eminent importance in natural products research, addressing the question why natural products display such a complex chemical information, what makes them often unique and what their characteristics are. Practical questions such as supply of natural substances and production optimization strategies are also covered.