Data Drain refers to the phenomenon where a device, such as a smartphone or tablet, loses battery power quickly due to excessive data usage or background processes. This can occur when apps continuously update, sync, or run in the background, consuming both data and battery life. Factors contributing to Data Drain include high screen brightness, location services, and notifications from various applications. Users can mitigate this issue by adjusting settings, closing unused apps, and limiting background data usage to extend battery life and improve overall device performance.