storage space

Hi: I own iPad 4 with iOS 10.3.3 installed. Device information tells me that out of 13.05 GB total (it is a 16GB model) only 1.37 GB are free. However, when I add together all space occupied by all programs (and their data), it all adds up only to 1.8GB. So my question is - what occupies 9.67GB...

My Specs: iPad Pro 9.7 32GB I am new to Apple products and I have no idea what I need or don't need in order for the iPad to work properly. Basically I'm asking for advice so I don't break anything. I bought the iPad for one use exclusively, to record my boys hockey games and post them on...