Reboot persistence is the ability of a modification or compromise to remain active after a device restarts. A change that disappears on reboot is temporary; one that returns without manual reactivation has persistence across reboot.
It matters because restarting a device often clears temporary code or state, so persistence can indicate a deeper foothold. In mobile security, an untethered jailbreak is one example: it is expected to remain jailbroken after reboot without a computer. Attackers may also seek reboot persistence to keep malicious software or unauthorized changes in place. Defenders can reduce risk by keeping devices updated, enforcing security policies, and checking for unexpected changes after restarts. A claim of reboot persistence should be verified across repeated reboots and on the specific device and software version involved.