Part I. Introduction 1. Ureases: an overview Part II. Historical aspects 2. Historical hallmarks in urease study 3. Plant urease genetics: A personal recollection Part III: Classes and special cases 4. Microbial ureases 5. Plant ureases 6. Jack bean urease 7. Fungal ureases Part IV. Activation, catalysis, inhibition 8. Urease: structure, function, catalysis, and inhibition 9. Inhibition of ureases: studies and applications 10. Non-catalytic activities in ureases Part V. Health applications 11. Ureases as drug targets in stomach ulcers and cancer 12. Ureases as drug targets in urinary tract infections 13. Ureases as drug targets in fungal infections Part VI. Biotechnological applications 14. Ureases and crop yield enhancement 15. Ureases as pesticides 16. Ureases for geotechnical applications 17. Ureases in the beverage industry 18. Ureases as biosensors