Why does the system always show 200 MB occupied by Photo, but my iPhone has zero photos? I am using an iPhone 5s 16 GB. iOS is updated to 8.4. I have no photos in my gallery. But the system always shows that 200 MB are used in Photo.  

What's the reason for this mismatch?
Try this.
1. Go to Settings > General > Date &amp; Time


Untoggle "Set Automatically"
Manually set the date a year or two in the past
Open "Photos"
Select "Albums"
If, like me, you had already cleared out everything from the Camera Roll and "Recently Deleted" folder, you'll smile to see that your "Recently Deleted" folder now has thousands of images back. Those are your phantom photos
Open it, "Select" and start deleting
Return to "Date &amp; Time" and fix your clock
Now, go back into Settings > General > Usage > Storage > Manage Storage. You'll notice your Photo &amp; Camera is empty if you deleted everything