Immunization is a process that helps protect individuals from infectious diseases by introducing a vaccine into the body. A vaccine contains weakened or inactive parts of a particular germ, which stimulates the immune system to recognize and fight the disease without causing illness. This prepares the body to respond more effectively if exposed to the actual disease in the future. Vaccines are an essential part of public health and have significantly reduced the incidence of diseases such as measles, polio, and influenza. Immunization not only protects the vaccinated person but also helps create herd immunity, which protects those who cannot be vaccinated, such as infants or individuals with certain health conditions.