CD16, also known as FcγRIII, is a low-affinity IgG receptor expressed on various immune cells, including natural killer (NK) cells, monocytes, macrophages, and neutrophils. As a member of the immunoglobulin superfamily, CD16 plays a crucial role in immune responses by binding to the Fc portion of IgG antibodies. This interaction triggers several important immune functions such as phagocytosis, respiratory burst, and antibody-dependent cellular cytotoxicity (ADCC), which are vital for defending against pathogens and cancer cells. CD16 exists in two forms, CD16a and CD16b, with CD16a being predominantly found on NK cells and monocytes, while CD16b is primarily expressed on neutrophils. Its ability to activate NK cells and enhance their cytotoxicity against target cells makes CD16 a significant target in cancer immunotherapy and antibody drug development.