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 and pharmaceutical industries use it to check for contaminants or measure analytes in quality control processes. Offers high sensitivity and specificity with relatively low sample volume requirements.