iPhones and iPads are stolen on a daily basis and while you can't always keep it from happening, you can make sure that a thief can't simply disable Find My iPhone leaving you without a way to track it by using Activation Lock. Not only that, it can also keep them from being able to restore your iPhone or iPad as new without your Apple ID, rendering it pretty much useless to them. Here's how:
That's it. Find my iPhone can not be disabled without the person knowing your iCloud password. As of iOS 7, anyone who wipes an iPhone or iPad needs the Apple ID it's tied to in order to activate the device. This is why it's important to disable Find my iPhone before selling your device to someone else.
Keep in mind that for this to work you need to not only be running iOS 7 or higher, you also need to have an iCloud ID set up on your iPhone or iPad. If you aren't sure what iCloud is or how to get started with it, you can check out our guide on everything iCloud:
Once you're done, come back here and make sure you enable Find My iPhone.