Why do I have 6.51GB of Other data on my iPhone 5? - 1

1.29 GB of Audio
189.9 MB of Pictures
3.48 GB of Apps
6.51 GB of "Other"
2.03 GB free

It says it's a 13.47 GB capacity phone. I have no clue why this data is so big. I believe it's corrupted data, and I have no idea how to clear the cache or fix it. I've backed up my phone, cleared everything, and then installed the back up again but it's no use. Why is this happening, and how do i fix this! I really don't want to have to buy a 32 GB phone just because of this enormous "Other" data.

Its saved data from your apps… Your messages, imessages…
and if your phone is jailbroken and you have installed tweaks, themes,… From cydia it will be shown as "other" on your space stats