Vaccines are biological preparations that help protect individuals from infectious diseases by stimulating their immune system to recognize and fight against specific pathogens, such as viruses or bacteria. They work by introducing a weakened or inactive form of the pathogen into the body, which allows the immune system to develop a memory of the pathogen and produce antibodies to combat it in the future. Vaccines have been instrumental in reducing the prevalence of many deadly diseases worldwide, such as measles, polio, and influenza. Ongoing research in the field of vaccines focuses on developing new and improved vaccines for emerging infectious diseases, enhancing vaccine efficacy and safety, and improving vaccine access and distribution to underserved populations.