CLIA (Chemiluminescence Immunoassay) is an advanced immunoassay technique that combines antigen–antibody interactions with chemiluminescent detection systems. This method provides high sensitivity, specificity, and wide dynamic range for the quantitative and qualitative analysis of various biomarkers, including hormones, infectious agents, tumor markers, and autoimmune antibodies. Due to its automation compatibility, rapid processing, and reproducibility, CLIA is extensively applied in clinical diagnostics, biomedical research, and laboratory medicine, offering a reliable alternative to conventional immunoassays such as ELISA.