You can use Find My iPhone to locate your iOS device if it’s lost or stolen. Apple’s free service uses your iPhone’s built-in GPS to let you track your phone’s location. Better yet, it lets you do things like lock your phone over the internet so the person who has it can’t use it, or remotely erase all of the data on your phone.
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If your iPhone has been stolen and you don’t have the Find My iPhone app installed on it, don’t panic. You don’t need the Find My iPhone app at all.
If your phone has been stolen and you don’t have the Find My iPhone app installed, I have good news: it doesn’t matter! The Find My iPhone app is not required to track your iPhone. To understand why this is the case, you need to understand that the Find My iPhone service and app are two different things.
The Find My iPhone service is cloud-based. That means the service is on the internet, not on your phone or in the app, and it can be used over the internet. This is an important point. The app is not what makes Find My iPhone work.