Immunoglobulins, also known as antibodies, are proteins that play a vital role in the immune system by recognizing and neutralizing foreign substances such as bacteria and viruses. There are five main classes of immunoglobulins: IgA, IgD, IgE, IgG, and IgM, each with its unique structure and function. Some synonyms for immunoglobulins include gammaglobulin, antitoxins, antiserum, antibodies, and immunoproteins. Gammaglobulin, another term for IgG, is often used when referring to the group of immunoglobulins that are isolated from human serum and used in medical therapy. Antitoxins and antiserums are specific types of immunoglobulins that can be used to treat specific diseases caused by toxins or infectious agents.