According to Apple, the data is collected "in order to learn places that are significant to you" and improve traffic routing services. The company says the data is stored locally on your iPhone and will not be accessed elsewhere or shared with anyone else.

But it's weird, fascinating, and just a little bit scary to realise that your phone contains a perfect record of where you've been in the last month or so. That includes the exact time you arrived at and left anywhere: your office, a bar, that person's house.