Part I. Important structures for functional dyes.- 1. Cyanine dyes.- 2. Squaraine dyes.- 3. Porphyrins and their analogues.- 4. Phthalocyanines and their analogues.- 5. BODIPY dyes and their analogues.- 6. Heteropolycyclic dyes.- Part II. Properties of functional dyes.- 7. Crystal polymorphism and dye aggregation in functional dyes.- 8. Photochromism.- 9. Two-photon absorption properties.- 10. Solid-state photoluminescence.- 11. Circular polarized luminescence.- Part III. Applications of functional dyes.- 12. Chemosensors and bioimaging.- 13. White-light emissive materials based on supramolecular approach.- 14. Photodynamic therapy.- 15. Photoenergy conversion (DSSC).- 16. Photoenergy conversion (OPV).- 17. Organic light-emitting diode.