Receiver Autonomous Integrity Monitoring (RAIM) is a system that uses satellites to help aircraft and ships to know where they are and where they are going. RAIM works by having the aircraft or ship's receiver (a device that receives data) collect information from satellites to measure the accuracy of the data it receives. The receiver compares the accuracy of the data as it was sent and as it was received, and can determine if the data is accurate or not. If it detects a problem, the receiver can alert the pilot or captain of the aircraft or ship about the problem. This allows for safer and more accurate navigation for pilots and captains, which can help save lives and keep everyone safe.