I had this same problem. I couldnt figure out what it was or where it was coming from. Delirium’s right as far as what other stands for. It also includes settings, cache and history, and texts. There was no way I was using 4 point something gig of other! If your in the same boat:
1) don’t panic. I’m here to save the day.
2) hook up your iPhone and click restore. It’ll ask you to back everything up, do that for sure so you don’t loose contacts and whatnot. You will loose music, but that’s it. Hopefully you got your music from your iTunes, if so its no big deal. After all that, you should be good to go. Hope this helps. Let me know if it works.