The abiotic characteristics of the environment - including temperature, oxygen availability, salinity, and hydrostatic pressure - present challenges to all biochemical structures and processes. This volume first examines the nature of these perturbations to biochemical systems and then elucidates the major adaptive strategies that enable organisms from all Domains of Life - Archaea, Bacteria, and Eukarya - to conserve common types of biochemical structures and processes across a wide range of environments. In addition to these conservative adaptations that foster a biochemical unity among diverse species, other adaptations can be viewed as innovative changes that enable organisms to exploit new features of the environment that may themselves be the result of biological activities.