A protein substance, also known as immunoglobulin produced by lymphocytes in response to a specific antigen (foreign substance, such as a virus), which has stimulated the body’s immune system.

The produced antibody recognises germs and foreign materials and helps to fight off infections to stop them from causing damage. After an infection has passed the lymphocytes remember how to make antibodies and will quickly eradicate the same type of germ if it enters the body again (immunity).