A restart prompt is a notice asking someone to close and reopen an application so an update or other change can take effect. Some updates cannot replace files or refresh active processes while the app is running, so the prompt signals that a restart is needed to complete the change.
In cyber security, restart prompts matter because users may postpone them, leaving fixes inactive while vulnerable software remains in use. Attackers can exploit known flaws on systems that have not completed updates. Defenders can reduce delays with clear guidance, managed update policies, and restart scheduling that limits disruption. Some software can apply updates with little interruption, but this does not remove the need for a restart in every case.