The three types of immunity are innate, adaptive, and passive.

immunity (n.) late 14c., "exemption from service or obligation," from Old French immunité "privilege; immunity from attack, inviolability" (14c.) and directly from Latin immunitatem (nominative immunitas) "exemption from performing public service or charge, privilege," from immunis "exempt, free, not paying a share" (see immune (adj.)). Medical sense of "protection from disease" is from 1879, from French or German. immune (adj.) mid-15c., "free, exempt" (from taxes, tithes, sin, etc.), from Latin immunis "exempt from public service, untaxed; unburdened, not tributary," literally "not paying a share," from assimilated form of in- "not, opposite of" (see in- (1)) + munis "performing services" (compare municipal), from PIE *moi-n-es-, suffixed form of root *mei- (1) "to change, go, move." Specific modern medical sense of "exempt (from a disease)," typically because of inoculation, is from 1881, a back-formation from immunity. Immune system attested by 1917. immunity (ih-MYOO-nih-tee) In medicine, the immune system’s way of protecting the body against an infectious disease. The three types of immunity are innate, adaptive, and passive. Innate immunity includes barriers, such as skin and mucous membranes, that keep harmful substances from entering the body. It is the first response of the body’s immune system to a foreign substance. Adaptive immunity occurs in response to being infected with or vaccinated against a microorganism. The body makes an immune response, which can prevent future infection with the microorganism. Adaptive immunity can last a person’s entire life. Passive immunity occurs when a person receives antibodies to a disease rather than making them through his or her own immune system. Passive immunity provides immediate protection but only lasts a few weeks or months.