Fluorophores, sometimes referred to as fluorescent dyes or labels, are molecules that absorb and emit light at specific wavelengths. They are used in a wide variety of applications, from biology and medicine to materials science and nanotechnology. Alternative words for fluorophore include chromophore, fluorochrome, luminophore, and luminescent probe. Chromophores are molecules that absorb light and are responsible for the colors we see in organic compounds. Fluorochromes are dyes that emit fluorescence under specific conditions. Luminophores include all molecules that emit light upon excitation, including both fluorescence and phosphorescence. A luminescent probe is a molecule used to detect or measure something through its emission of light.