Ureases: Foundations, Classes, and Applications provides a thorough, practical analysis of ureases—enzymes of growing relevance across a range of biotechnological applications and drug discovery. Unique in many aspects, ureases are one of the few enzymes to have nickel in their active sites. This book covers all aspects of this enzymatic class starting with foundational overview and then providing historical urease research and current state, from basic biochemistry to the use of ureases as hallmarks in enzymology, crystallography, and bioinorganic chemistry. The different classes of ureases, structurally diverse but chemically equivalent, are individually discussed. The multi-protein, multi-step activation of ureases (with chemical modification of residues, transport, and transfer of nickel ions) are examined in-depth, along with the catalytic mechanisms of ureolysis and its inhibitors. The final two sections of the book address multiple applications of ureases in health and biotechnology, respectively, going from gastric ulcer treatment to architectural uses in buildings and engineering. Future applications and next steps in research are also considered.