Definition - What does Immunity mean?
Immunity is the ability of animals and plants to resist infections, disease, or allergic reactions. Immunity can be active or passive. Both active and passive immunity, can be acquired naturally or artificially. Without the body's ability to become immune to certain illnesses and substances, the body would be quickly overwhelmed. Individuals with weakened immune systems usually have low immunity and become sick more often.
SureHire explains Immunity
Broadly speaking, immunity is active or passive. Both these can be developed naturally or artificially. When our body develops antibodies as a reaction to a naturally occurring infection, the immunity is natural active immunity. The immunity developed due to vaccination is artificial active immunity because the actual infection did not develop but the body was tricked into producing the needed antibodies to create an immunity.
Passive immunity is the acquisition of immunity from outside. An infant gets these antibodies from its mother in utero or through antibodies contained within breast milk. Artificial passive immunity can be developed by the injection of small doses of substances such as allergens, over a long period of time, in order to gradually develop a tolerance and then immunity.