What is other on my iphone in itunes?

I'm trying to make room on my iphone and it is showing me I have hardly any space left so I'm looking at the bar in itunes and it's telling me where all my storage is going and it shows I have 4.02 GB going to other and I was wondering what could be other, why its taking up that much space and how to I get rid of it?

Yeah, I agree 100%. That's so true.