What is a vaccine that makes people immune to diseases?

In the simplest terms posiible you need to know that vaccines work WITH your immune system by building up your body's ability to DEFLECT unwanted diseases from your body. The vaccines are used to build up your resistance to the known pathogens. For instance a "flu" shot consists of pathogens of the influenzas the Center for Disease Control (and the World Health Organization) predict will be in season and should be included in the "flu shot".