The increasing size of "Other" data on an iPhone, iPad, or iPod Touch has been a serious issue ever since iOS 5, and it can cause your available disk space to go way down for no apparent reason. The "Other" data on an iPhone or iPad originally contains only system files: the OS, database files, settings, core data, the native apps, etc. Then, the “Other” portion grows from there, so as you install more apps, add more personal files, send more text messages, and generally use your device for anything, this "Other" section grows just like any other operating system.
It is typically under about 1 or 2 GB, but it can grow to several more GB's due to this Apple bug, and when this happens, Apple's only recommendation is to restore your iPad or to factory settings which will wipe it clean and remove any of your personal data and settings.
Most of us are not interested in starting over from scratch with their iPhone or iPad, so If you are one of these people who prefers not to restore your iPhone or iPad to factory settings, you could try using iExplorer find out what data is to blame for this and to see if you can at least get the size of "Other" data reduced. Here are some places to look for large files causing the "Other" data size to increase:
- Rented movies or TV shows from the iTunes Store that you've watched on your device might still be taking up space after the rental time has expired. You can look for any of those in Media/Purchases folder or Media/iTunes_Control folder.
- Deleted text message attachments still left on your device. There is a known Apple bug where text message attachments are still left on your device even after you delete the conversation in your Messages app. To look for these, just go to the Backups section > Backup Explorer > MediaDomain/Library/SMS/, and they'll all be in the Attachments and Parts subfolders. If you do end up finding large files in that Attachments folder from a conversation that you know you already deleted, the only way to remove them is if you restore your device to factory settings or Jailbreak your device and gain Root folder ("/") access since those attachments are stored closer to the root of iOS which Apple prevents anyone from accessing unless you hack (Jailbreak) iOS. The reason that iExplorer's Backups section can at least display them is because iTunes backs up those files, and the Backups section is extracting the data from an iTunes backup on your computer.
If you would like to view the size of a folder in a file system view such as Media and Apps, you can just right-click on one and choose "Scan Contents" (PC) or "Update Size" (Mac) which will display the size of that folder in the Size column.
To get a detailed list of how much storage each app is taking up, you can do this on your device by tapping Settings > General > Usage, and then tap Show all Apps to see the full list. Then, tap on an app to see more details. Then, just go into that app directory in iExplorer to delete any unnecessary documents, though I do recommend being cautious about deleting important app files, and we'd recommend performing an iTunes backup prior to deleting anything, just in case.