Immunization refers to the process by which a person is made immune or resistant to an infectious disease, typically through the administration of a vaccine. Vaccines contain small amounts of weakened or inactivated pathogens, or parts of them, which stimulate the body's immune system to produce a response that helps protect against future infections by the actual pathogen.
Immunization is one of the most effective ways to prevent infectious diseases and their spread within communities. It has been responsible for the eradication or control of many life-threatening illnesses, such as smallpox, polio, measles, and tetanus. Immunizations are recommended for people of all ages to help protect them from serious diseases and keep them healthy.