Q. What are artificial active immunization and natural active immunization?

Natural active immunization is that in which a previous natural infection induces the primary immune response specific memory cells are produced and the individual becomes immune to new infections with the antigen. This is what happens in diseases that affect people only once in life like chickenpox and mumps.

Artificial active immunization is that in which the primary immune response is caused by the inoculation into an individual of specially prepared antigens this is the case with vaccines.