Wood's light (or "Wood's lamp") is a diagnostic technique used in dermatology that consists of shining ultraviolet light (approximately 365 nanometer) on the skin of the patient, and observing the fluorescence.
Wood's light is helpful in diagnosing Fungal infections (Microsporum audouini), Bacterial infections (Corynebacteriium minutissimum, Pseudomonas) and Pigmentary disorders.