Used in laboratories to detect and quantify substances such as peptides, proteins, antibodies, and hormones in biological samples. Commonly applied in medical diagnostics to identify diseases like HIV, hepatitis, and COVID-19 by detecting specific antigens or antibodies. Also used in research settings to study immune responses and protein expression. Food industry employs ELISA kits to test for allergens such as peanuts or gluten. Provides a sensitive and high-throughput method for screening large numbers of samples with relatively low cost and ease of use.