You might have heard that some iPhones suddenly reboot on their own. It turns out, this isn't a glitch, but a new security feature Apple has added to iOS 18. The feature, called "inactivity reboot, " makes your iPhone restart if you haven't unlocked it in 72 hours. This is a clever move by Apple to make your phone even more secure.

Here's what happens. If your iPhone is locked and no one has entered the passcode for three days, the phone will reboot. This is a big deal because it makes it much harder for anyone who tries to access your data without your permission—like thieves or even law enforcement—to get in.

When your iPhone reboots, it moves into a more secure state. Certain data that was partly accessible when your phone was off but not unlocked (this is what experts call the "After First Unlock" or AFU state) becomes fully encrypted again. This means that even if someone manages to bypass the lock screen, they won't be able to get to your data without knowing your passcode.

Scientists and phone forensics experts have confirmed this feature. Jiska Classen, a researcher, even made a video showing what happens when an iPhone is left alone for three days without being unlocked. Classen explained that although this makes it tougher for law enforcement to access data from criminals' phones, it doesn't completely lock them out. There's still time for experts to figure out how to get the data.

Apple has always been serious about phone security. They've added many features over the years that make it hard for anyone to break into your phone. In 2016, there was a big fight when the FBI wanted Apple to create a way to unlock an iPhone from a mass shooter. Eventually, another company helped them do it.

Remember the two states your iPhone can be in: "Before First Unlock" (BFU) and "After First Unlock" (AFU)? In BFU state, your data is very secure, locked away with your passcode. In AFU state, some parts of your data might be easier to access. This new inactivity reboot feature moves your phone back to the very secure BFU state after three days.

So next time your iPhone restarts when you haven't used it for a few days, know that it's just your phone being extra careful to keep your data safe.

iPhones Now Reboot to Stay Safe: How Apple's New Feature Works

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