iOs devices have a file system, and it's a hierarchical file system like real computers have.  (Hierarchical:  files are organized into directories (aka folders) and folders can reside inside other folders.

However, most of the file system is locked to the user.  (iOS devices do not have superusers or administrative or root or whatever you want to call it.)

When we run the iPhone simulator, the iOS hard drive is simulated in folders on the Mac hard drive, but because it is a simulator, the Mac still can't directly access most of these files.

However, you do have access to a "Documents Folder" on your iOS device where you can store files and retrieve them later.

So, some of what we're doing here is simply copying data from the hard drive to the device.