Beacon (RUM Beacon)

A beacon is a small, asynchronous packet of data that a website sends to a server for tracking or analytics purposes. In the context of Real User Monitoring (RUM), a RUM beacon is sent from the user's browser back to the RUM data collection server, containing the performance metrics for that user's page view. The Beacon API in modern browsers is designed to send these beacons reliably without slowing down the user's next navigation.