Find My Friends is an app made by Apple that lets you track the location of your friends and family so you can find out their whereabouts at any time of the day, but it can also be a real privacy concern.
While some people enable this feature voluntarily so that their family members can keep tabs on them or so that friends can meet up with one another, others have the feature enabled on them behind their backs so their significant others can stalk them.
If you’re paranoid about whether or not you’re being tracked, then you need a new free jailbreak tweak called AntiTracker.