What is the relationship between immunity and vaccination?

You get immunity by having a vaccination or by having the infection itself.

The vaccination is the introduction of the pathogen in tiny amounts to kick start your immune system so it knows how to deal with the real thing if you encounter the germ in the environment.

A vaccine is the medicine made to introduce the pathogen (infection-causing "bug") into your body in a vaccination.

Having immunity is how your body prevents a second infection by the same germ. The first time you catch the germ (or get a vaccination for it), your body responds to cause immunity, so if you run across the same exact germ again later, your body already knows how to prevent an infection again.

See the related questions below for more about vaccines and vaccinations.