What is ' other ' on iphone?

My phone has been saying that it doesn't have any room to hold pictures, naturally I thought I should delete some. I did but deleting them didn't help. When I plug my iphone (4) into my computer, itunes pops up and it shows how much space I have and what is taking it up. " Audio, Photos, Apps and Other " It's saying that " Other " is pretty much taking up the entire thing. I have no idea what " Other " is. Can anyone help me?

Here is how you fix it
1: trow your phone agents the wall as hard as possible
2: buy a new phone
3: your phone is working again

"other" is the operating system itself, text messages, contacts, phone calls, records, etc., internet browser history, cookies, etc., and any other random junk that has accumulated on your phone.

I would restore the iPhone to factory settings (backing it up to iTunes, of course), and put everything back on. That should minimize the "other" space.