The enzyme-linked immunosorbent assay (ELISA) is a laboratory technique used to detect and quantify proteins, hormones, or antibodies in a sample. It involves immobilizing an antigen on a solid surface, adding a sample that may contain antibodies, and then introducing an enzyme-linked secondary antibody that binds to the target. A substrate is then added, which reacts with the enzyme to produce a measurable signal, usually a color change. ELISA is widely used in various fields, including clinical diagnostics, biomedical research, and food safety. Its sensitivity and specificity make it a valuable tool for detecting diseases, monitoring immune responses, and ensuring product quality.