Vaccines are biological preparations that provide acquired immunity to a particular infectious disease. They contain antigens that stimulate the body's immune system to recognize and fight pathogens, such as viruses and bacteria. Vaccination is a crucial public health tool that has led to the eradication or control of many diseases, including smallpox and polio. The process of vaccination involves administering a vaccine, which can be in the form of a shot, oral dose, or nasal spray. Vaccines not only protect individuals but also contribute to herd immunity, reducing the spread of diseases within communities. This collective immunity is vital for protecting those who cannot be vaccinated, such as infants and individuals with certain medical conditions.