Rhodamine derivatives represent classic red-emitting fluorophores (λem 550-600 nm) with outstanding brightness and photophysical robustness. Their rigid xanthene core ensures high quantum yields (>0.9) and moderate environmental sensitivity. Modern derivatives (e.g., TAMRA, TRITC) feature improved photostability and reduced triplet-state formation. With amine-reactive groups, they serve as premium labels for confocal microscopy, FISH, and protein tracking. Their tunable emission and excellent performance in fixed cells maintain their status as essential tools in core imaging facilities.