Active immunity means that the body’s immune system is able to produce antibodies on its own and has the ability to produce antibodies and defeat diseases when they invade. This is in contrast to passive immunity, which is the direct administration of antibodies to the body from exogenous sources. Although the body can be immunized for a period of time, the body’s immune system does not have the ability to produce antibodies. There are two ways to obtain active immunity: first, by being directly infected, such as having had measles or chicken pox once, and not being infected again in the future, because the body has acquired the ability to be actively immune. Second, through vaccination. If you get the chickenpox vaccine or measles vaccine you can also get the same antibodies, but without symptoms such as disease.