A rapid, preliminary microscopic technique in which a fresh sample (vaginal discharge, stool, sputum, or skin lesions) is placed on a microscope slide with a drop of normal saline or potassium hydroxide (KOH). The slide is covered with a lid and examined directly under a light-field microscope to visualize motile organisms (such as Trichomonas vaginalis), yeast cells (such as Candida), white blood cells, or crystals. It is primarily used as a rapid screening test.