Immunogens are substances that can trigger an immune response in an organism. They are the molecules that activate the immune system and help it recognize and destroy infectious agents, such as bacteria or viruses. There are several synonyms for immunogens, such as: antigens, immunizing agents, immunostimulants, immunostimulatory agents, immunogenic substances, and immune activators. Antigens are molecules that also trigger an immune response but are usually recognized by specific antibodies, whereas immunogens are recognized by a wider range of immune cells. Immunostimulants and immunostimulatory agents are substances that boost the immune response, while immunogenic substances and immune activators activate the immune system. All of these terms refer to the same type of molecule that is essential in fighting off infections and maintaining good health.