Immunoglobulin G (IgG) is a type of antibody. Representing approximately 75% of serum antibodies in humans, IgG is the most common type of antibody found in the circulation.IgG molecules are created and released by plasma B cells. Each IgG has two antigen binding sites.Antibodies are major components of humoral immunity. IgG is the main type of antibody found in blood and extracellular fluid allowing it to control infection of body tissues. By binding many kinds of pathogens such as viruses,