This document discusses immunity and immunization. It defines immunity as the body's ability to fight pathogens through recognition, destruction, and elimination of antigens. There are two types of immunity: innate and acquired. Immunization is the process of inducing immunity artificially by administering vaccines or antibodies. Vaccines work by exposing the immune system to antigens without causing illness. The document also discusses the components of immunization programs including vaccines, cold chain storage and transport, record keeping, adverse events monitoring, and factors influencing vaccine effectiveness.