Our understanding of how vaccines work is based on their ability to stimulate the body's immune response without causing disease. Vaccines typically contain weakened or inactivated parts of the pathogen or its genetic material. When administered, they trigger the immune system to produce antibodies and memory cells that recognize and fight the pathogen if exposed in the future. This process enhances immune memory, providing long-lasting protection. Vaccines play a crucial role in controlling infectious diseases and are a key element in public health initiatives.