A comprehensive review of fluorescent dyes includes the structures and properties of the most important classes. Fluorescent dyes absorb light in the visible spectrum and exhibit intense light emission. The primary types of fluorescent dyes include carbonyl dyes (coumarins, naphthalic acid derivatives, perylenes, benzanthrone, anthraquinones, bezoxanthones, and benzothioxanthones), rhodamines and related compounds, and hydrocarbon and methane compounds. Fluorescent dyes are used as daylight fluorescent pigments, as dyes for fabrics and plastics, as dyes for lasers, for nondestructive materials inspection, in solar collectors, and for analytical, biological, and medical applications.