This document discusses different types of immunity. It describes innate immunity as the first line of defense against infection that is genetically determined and not related to previous exposure. Innate immunity includes anatomical, physiological, chemical, and biological barriers like skin, mucous membranes, stomach acid, and phagocytic cells. Acquired immunity develops from exposure to pathogens and results in antigen-specific active and passive immunity. Active immunity is long-lasting and includes natural immunity from infection or artificial immunity from vaccines. Passive immunity provides short-term protection through transfer of antibodies from mother to fetus or artificially through antiserums.