iPod space!!

I have a 4th generation 8gb iPod touch. Two questions:
What is 'other' when you get on iTunes and see your total spaced used?
Why do all of a sudden I have no space? I haven't gotten a new app in a long time (I actually deleted some), I went through and deleted pictures...

I'd like to know this one also. I also would like to know what I'm getting for the extra icloud space I paid for?