A cosmonaut is a person trained to travel and work in space. The term is primarily used in Russia and refers to astronauts who are part of the Russian space program. Cosmonauts undergo rigorous training to prepare for the challenges of space travel, including learning how to operate spacecraft and conduct scientific experiments in a zero-gravity environment. Cosmonauts often participate in missions aboard the International Space Station (ISS), where they conduct research that benefits life on Earth. Their work helps scientists understand more about space, human health, and the universe, contributing to advancements in technology and our understanding of astronomy.