Scientific breakthroughs are significant discoveries or advancements that change our understanding of the world. These can include new technologies, medical treatments, or theories that solve complex problems. For example, the development of the vaccine for polio in the 1950s drastically reduced the incidence of this disease, saving countless lives. Another notable breakthrough is the discovery of penicillin by Alexander Fleming in 1928, which marked the beginning of modern antibiotics. This discovery transformed medicine by providing effective treatment for bacterial infections, leading to improved health outcomes and increased life expectancy worldwide.