Storage space on 32g iPhone 5

I recently had to replace my iPhone 5 with a new one. Everything was backed up through iCloud, and I synced everything in my iTunes as well. When everything was originally synced, I had used up 13 gb of audio, basically no photo, 1.15 gb of apps, and 2.14 gb of "other." While I don't know what the category "other" consists of, I just plugged my phone into my iTunes again and now the "other" jumped from 2.14 to 6.13 gb taken up. I was wondering if anyone knows what that is, why there's so much, and how I can get rid of it? Thanks!