1. The discovery of FGF23 - a historic view: genetic disorders of hypo- and hyperphosphatemia 2. FGF23 - an established master regulator of phosphate metabolism 3. FGF23 - more than a phosphaturic hormone 4. The regulation of FGF23 production in bone and outside of bone 5. Klotho-dependent actions of FGF23 - targets, signal transduction and cellular effects 6. Klotho-independent actions of FGF23 - targets, signal transduction and cellular effects 7. The experimental detection of FGF23 responsiveness and effects 8. FGF23 and bone disease 9. FGF23 and kidney disease 10. FGF23 and heart and vascular disease 11. FGF23 and inflammation, anemia, and iron 12. FGF23 and infectious diseases 13. FGF23 and lung disease 14. FGF23 and neuro-cognitive disorders 15. FGF23 as a drug target 16. FGF23 - resolved issues, remaining controversies and future questions - a clinician's perspective 17. Klotho - the discovery of the FGF23 co-receptor 18. Klotho - an FGF23-independent hormone 19. Klotho and aging phenotypes 20. aKlotho gene and protein measurements in humans and their role as a clinical biomarker of disease 21. Structural Basis of FGF23 Hormone Signaling 22. Klotho - open questions, controversies and future perspectives 23. The crosstalk between phosphate, FGF23 and klotho in the regulation of tissue homeostasis in health and disease