Final answer:
Artificially acquired active immunity occurs when a person is vaccinated with a substance that contains weakened or inactive parts of a pathogen, leading to the production of antibodies and immune memory without causing disease.
Step-by-step explanation:
Artificially acquired active immunity is what occurs when an animal, including humans, is vaccinated. Through the process of vaccination or immunization, a person is intentionally exposed to a vaccine that contains weakened, inactivated pathogens, or key pathogen antigens. This deliberate exposure stimulates the body's adaptive immune system to produce antibodies and memory cells specific to the pathogen without causing the illness. Vaccines thus create a state of immunity that prepares the body to fight off the actual disease-causing organism if encountered in the future.
The vaccine serves as a critical tool in this process, providing the necessary components to trigger the immune response. A successful vaccination program can lead to long-lasting protection against the disease and is responsible for the control or eradication of many infectious diseases, such as smallpox, polio, measles, and whooping cough.