Human gamma globulin, also known as immune globulin or IgG, is a protein found in the blood that helps to fight against infections and diseases. There are several synonyms for this important protein, including immunoglobulin G, serum globulin, and gamma globulin. These terms are commonly used interchangeably depending on the context, with gamma globulin typically referring to the fraction of serum that contains IgG. While there are several types of immunoglobulins in the human body, IgG is the most abundant, making up around 70-80% of all antibodies. With its ability to neutralize toxins, stimulate phagocytosis, and activate complement, human gamma globulin plays a key role in maintaining a healthy immune system.