Immunoglobulin (Ig) is another name for an antibody, which is a type of protein made by the immune system to help identify and neutralize foreign substances like bacteria, viruses, or other harmful agents. Immunoglobulins have a Y-shaped structure that allows them to specifically recognize and bind to unique parts of these foreign substances, called antigens. There are several classes of immunoglobulins, including IgG, IgA, IgM, IgE, and IgD, each with different roles in the body’s defense system. For example, IgG is the most common and provides long-term protection, while IgA is found mainly in mucous membranes like those in the nose and gut. Immunoglobulins are essential for maintaining health by helping the body respond to infections and other threats.