When syncing using itunes.... OTHER what is "other"

The "Other" is the space taken up by the Firmware Files and the Database File that lists which music file is which. The Database File is needed because all the music you put on is renamed into 4 letter Code-words to help fight music-sharing piracy, and the Database File tells the iPod what songs are on it, all of the info associated with those songs, and where to find those songs.

If you are referring to the Capacity Line in itunes when the phone is connected. Other is Contacts, stored emails, and web clips that are saved to the phone.

Also "other" also holds failed sync data.

example: syncing a large amount of data your phone resets and iTunes reports that it can no longer write to the disk. That failed data now rest in the "other" section and can no longer be used and will take away from your total storage area. The only way to free up this space is to reset the phone from the settings > general menu on the phone.

With the recent 1.1.3 its not uncommon to see others in the 180-200mb range.

So if you have a rather large other (ie 500mb, 1GB, 2GB or more) you more than likely had the phone restart in the middle of the sync.

Okay, so how do you clear out that failed sync data? My iPhone lists 1.20 GB of "Other", which has been there for the last few syncs in a row. Should I restore the phone to reclaim that space?

Im thinking that will come back anyway because when you restore, everything is sync back to your phone...

If you do a Restore it will clear out the bad data in Other.