Why does the iPhone Plus have two cameras on the back?

Why does the iPhone Plus have two cameras on the back? - 1

For its depth imagery, mostly for use with its Portrait mode feature.

In case one stops working

  • Why do old cameras have awful pic quality although the MP is higher then my phone? So I have an old compact camera with 12.1 MP, which i got around 2010 or 2011. I recently got a charger to charge my old camera to try out cuz I thought it would have a better quality then my iPhone 7 Plus (12MP). But when I tried taking pictures with my old camera it looks like it only have 1MP. I'm so confused because the MP are the same yet the photo quality has such big difference. Any idea why?
  • What cameras have similar quality as Iphone 5? I'm looking for a camera for portrait and scenery photos. I really like the quality of my phone, but I would like something with better zoom that I can put a strap on and get a lot closer. Any ideas? It does not need to be super fancy and expensive, just similar to my phone.
  • Two different computers, two different iTunes.can I use the same Apple ID? I have iTunes on my computer that I use for my iPhone, and my mon just got an iPod Touch and wants me to fill it for her. I'm going to use her computer to do this, which currently does not have iTunes. Once I download iTunes, can I use my own Apple ID to download songs and apps onto her iPod? Is it possible to do that without disturbing what's on my phone, or do I have to make a whole new iTunes account for her?
  • My iphone 5s' cameras have both stopped working? About 2-3 days ago my front-facing camera on my iphone 5s stopped working, and now today the back camera has stopped working also, so whenever I go to the camera application, it just shows black. The only thing that has happened to my phone is that it got a little water in it about 2 weeks ago, but both cameras were working fine. Any suggestions welcome.