What is Active immunity and Passive immunity ?

$(1)$ When a host is exposed to antigens, which may be in the form of living or dead microbes or other proteins, antibodies are produced in the host body.

This type of immunity is called active immunity.

$-$ Active immunity is slow and takes time to give its full effective response.

Injecting the microbes deliberately during immunization or infectious organisim gaining access in the body during natural infection induce active immunity.

$(2)$ When ready-made antibodies are directly given to protect the body against foreign antigens/agents. It is called passive immunity.

The yellowish fluid colostrum secreted by mother during initial days of lactation has abundant antibodies $(IgA)$ to protect the infants.

The foetus also receives some antibodies $(IgG)$ form the mother, through placenta during pregnancy.