TNFRSF11B, also known as osteoprotegerin (OPG), is a member of the tumor necrosis factor receptor superfamily involved in regulating bone metabolism and immune responses. It functions as a decoy receptor for RANKL (receptor activator of nuclear factor kappa-Β ligand), inhibiting osteoclast differentiation and bone resorption by blocking RANKL-RANK interactions. Dysregulation of TNFRSF11B is linked to osteoporosis, vascular calcification, and cancers with skeletal metastases. Antibodies targeting TNFRSF11B are primarily used in research to study its role in bone homeostasis, inflammatory diseases, and tumor microenvironment modulation. In clinical contexts, anti-TNFRSF11B antibodies may have therapeutic potential for conditions like postmenopausal osteoporosis or rheumatoid arthritis by restoring RANKL/OPG balance. However, excessive inhibition could risk unintended effects, such as hypercalcemia or reduced vascular integrity. Commercially available TNFRSF11B antibodies (monoclonal or polyclonal) are widely utilized in techniques including ELISA, Western blot, and immunohistochemistry to quantify protein expression or map tissue distribution. Recent studies also explore its diagnostic value as a biomarker for cardiovascular diseases and certain cancers. Challenges remain in optimizing antibody specificity to avoid cross-reactivity with other TNF receptor family members and ensuring consistent reproducibility across experimental models.