Fluorescence assays are laboratory techniques used to detect and measure the presence of specific substances, such as proteins or nucleic acids, by utilizing fluorescent molecules. When these molecules are exposed to light of a certain wavelength, they emit light at a different wavelength, allowing researchers to quantify the target substance based on the intensity of the emitted light. These assays are widely used in various fields, including biochemistry, molecular biology, and clinical diagnostics. They offer high sensitivity and specificity, making them valuable for applications like drug discovery and environmental monitoring.