Did you know your iPhone tracks you everywhere you go?
Go to Settings -> Go to Privacy -> Location Services -> and scroll all the way down to the last item, System Services. Open and scroll down to the bottom of System Services and tap Frequent Locations. Apple has hidden a feature here so that your iPhone tracks you everywhere you go. This depletes battery power by constantly tracking your whereabouts, so turn it off unless you want to be tracked. Then go back to the bottom of System Services and turn on the Status Bar Icon, so that you will know when one of your Apps is tracking you.
If you want to prevent your Apps from tracking you, you will need to read this article, which has many tips on saving iPhone battery power: The iPhone Battery Fix