Have you determined the size of all the applications, system files, device-owned software
and that which is not added by you into the device's total occupied storage space, then
do some vague math to see what the difference is between your created content & that?
In the more complex Mac OS X, the Other includes most system files among other content
and the computer may not function properly without it. There probably are some articles in
Support online that answer the question, put one way or another: "What is Other content?"
While I know I've read about this, and there would be some similarity between iOS + OS X
in these kinds of files, I do not remember those details. Maybe because at the time I was
using an older OS X version that 'just works' and never needs that kind of interrogation.
I do know you usually would not erase 'other', if you could; it may affect how the device works.
In OS X there is this support article; maybe one exists for iOS:
•OS X: What is "other" space in About This Mac? - Apple Support
The topic of iOS and Other come up in this search result:
https://www.google.com/?gws_rd=ssl#q=clean+ios+other+data
Here's the results of the OS X and Other topics. Slightly different:
https://www.google.com/?gws_rd=ssl#q=clean+OS+X+other+data
Be wary and avoid third-party software whose theme is a 'free download' from questionable
sites or sources; and installs stuff that may affect your system, some of it is adware/malware.
Good luck & happy computing!
edited 2x