A direct and rapid microscopic examination to detect fungal components (such as hyphae or fungal filaments, and yeast cells) in skin, hair, or nail samples. The sample is treated with a 10–20% potassium hydroxide (KOH) solution, which dissolves human keratinocytes (dead skin cells) while leaving the fungal structures intact and clearly visible under the microscope, thus facilitating the rapid diagnosis of superficial fungal infections.