[General] What counts as 'Other files'?

What counts as 'Other files'?

I'm not the biggest expert when it comes to phones.

But I connected my iPad to iTunes the other day, I learned I had a lot of space being used up in the 'Other files' tab and learned it's related to unused Cache information and stuff, and other corrupted files etc, and the way to get rid of it was to backup my iPad, restore it and put the backup back on the iPad - which worked.
So I decided to connect my phone to my PC for the first time in a long while to find a similar problem on my phone, but would it be a similar issue? iTunes has an Apps tab unlike Android so I'm not sure if it would be space used by them, or the same problem as the iPad.

Furthermore, if I'm going to do the backup then restore thing, how do I backup my phone? PC Companion is a freaking pain in the *** and I hate it, constantly telling me to update when it has been etc. So I really don't know how to work it. Help would be much appreciated.

Phone is an Xperia Play R800 btw.

.

forum.xda-developers.com