Fc receptor is a protein belonging to immunoglobulin superfamily that contributes to the protective functions of the immune system. Fc receptor is found on the surface of certain cells - including B lymphocytes, natural killer cells, macrophages, neutrophils and mast cells. Its name is derived from its binding specificity for a part of an antibody known as the Fc portion. Fc receptors bind to antibodies that are attached to infected cells or invading pathogens. There are many kinds of Fc receptor based on the type of antibody that they recognize. Their activity stimulates phagocytic or cytotoxic cells to destroy microbes or infected cells by antibody-mediated phagocytosis or antibody-dependent cell-mediated cytotoxicity.