Any foreign substance that enters the body and induces an immune response is called?

An antigen is any foreign substance that enters the body and induces an immune response. Antigens can be proteins, carbohydrates, lipids, or nucleic acids. They are typically found on the surface of bacteria, viruses, and other microorganisms. When an antigen enters the body, it is recognized by the immune system and triggers the production of antibodies. Antibodies are proteins that bind to specific antigens and help to neutralize them.