Book excerpt: This book provides in-depth reviews of the role of Rhizobium in agriculture and its biotechnological applications. Individual chapters explore topics such as: the occurrence and distribution of Rhizobium; phenotypic and molecular characteristics of Rhizobium; impact of Rhizobium on other microbial communities in the rhizosphere; N2-fixation ability of Rhizobium; Rhizobium and biotic stress; Rhizobium-mediated restoration of an ecosystem; in silico analysis of the rhizobia pool; further biotechnological perspectives of Rhizobium.