The advent of metagenomics has had a dramatic effect on the way we view and study the microbial world. By allowing the direct investigation of the vast majority of bacteria, as well as viruses and fungi, irrespective of their culturability and taxonomic identities, metagenomics has not only changed microbiological theory and methods but has also challenged the classical concept of species. This newly evolved biological field has proven to be rich and comprehensive and is making important contributions to ecology, biodiversity, bioremediation, bioprospection of natural products, medicine, and many other fields. The diversity of facets of metagenomics as well as the multiplicity of its potential applications makes it difficult to find an ample but at the same time ordered account of this new discipline. This book intends to address in a coherent manner the multiple aspects of metagenomics, from new theoretical insights to the more recent applications, through to the dynamically developing methods of data acquisition and analysis. The book is aimed at researchers currently performing metagenomics studies as well as students and scientists interested in starting research in this field. Book jacket.