How to check if my iphone is jailbroken?

I lent my iphone 5 to a friend and I think he has jailbroken my iphone but I'm not sure so how do I check?

Why? Does it have your content on it? Does it refuse to sync with your computer?
When in doubt, restore from last cloud backup.

Check if cydia is installed. If it is then you know its jailbroken. If you find it jailbroken just use the USB charger to plug it in the computer then click iTunes after that click restore that's it.

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