The International Earth Rotation and Reference Systems Service (IERS) is an organization that monitors and maintains the Earth's rotation and its reference systems. Established in 1987, IERS provides essential data for various scientific fields, including astronomy, geodesy, and navigation. It helps ensure accurate timekeeping and positioning by tracking changes in the Earth's rotation and gravitational field. IERS is responsible for producing the International Celestial Reference Frame (ICRF) and the International Terrestrial Reference Frame (ITRF). These reference frames are crucial for precise measurements and applications, such as satellite positioning and global positioning systems (GPS). By providing reliable data, IERS supports scientific research and technological advancements worldwide.