A "reboot loop" is a situation where an electronic device, such as a computer or smartphone, repeatedly restarts itself without being able to fully boot up. This can be caused by a variety of issues, including software problems or hardware failures. The device gets stuck in a loop, continuously trying to start up and then shutting down again, without reaching the point where it can fully operate. A reboot loop is typically an indication of a serious issue that requires troubleshooting or repair.