Estimated Time of Arrival (ETA) is the projected time when a vehicle, shipment, or person is expected to reach their destination. ETAs are fundamental to transportation planning and logistics. Transit systems provide ETAs through real-time arrival displays at stops and mobile apps, helping riders plan their trips. Navigation systems calculate ETAs based on distance, traffic conditions, and route characteristics. Emergency services use ETAs to coordinate response and inform callers when help will arrive. In project management and delivery services, ETAs set expectations for completion or arrival. ETAs are estimates subject to change based on conditions—traffic incidents, weather, or operational issues can delay arrivals. Modern technology enables increasingly accurate real-time ETAs by incorporating current conditions, but uncertainty remains inherent in any prediction about future events.