This book addresses in a coherent manner the diverse and multiple aspects of metagenomics and the multiplicity of its potential applications. Renowned authors from around the world have contributed chapters covering the new theoretical insights, the more recent applications, and the dynamically developing methods of data acquisition and analysis. Topics include: Conceptual frameworks, tools and methods, integration of complementary approaches, horizontal gene transfer, analysis of complex microbial communities, public data resources, plant-microbe interactions, bioremediation, industrial bioproducts, archaeal metagenomics, bioprospecting novel genes, the human microbiome, and philosophical themes in metagenomics.