The International Earth Rotation and Reference Systems Service, or IERS, is an organization that monitors and provides data on the Earth's rotation and its reference systems. Established in 1987, it plays a crucial role in maintaining accurate timekeeping and positioning systems used globally, such as GPS and other satellite navigation systems. IERS collects and analyzes data related to the Earth's rotation, including variations caused by factors like gravitational forces and seismic activity. This information is essential for scientific research, navigation, and various applications in fields such as astronomy and geodesy, ensuring that our understanding of the Earth remains precise and up-to-date.