I have a MacBook Air, 2009, just tried updating to iOS El Captain and I got a message saying I didn't have enough space. I have 121 GB storage so surely I have enough space. I looked in About This Mac and its stating that I have 88 GB in other. What is this and how do I get rid of it? I went through my photos (which I need to backup on flash drives anyways) deleted plenty, deleted all unnecessary music, applications, ect. I do not know where all of this space is being used. 88 GB seems large.