The International Space Station (ISS) has been continuously occupied by rotating crews of astronauts and cosmonauts for over 20 years. The ISS was first occupied on November 2, 2000, and has been continuously inhabited since then, making it the longest-serving human-made object in low Earth orbit. Over the course of its 20 years of operation, the ISS has played a vital role in space exploration, scientific research, and international cooperation.