capacity low on 5s iOS 8.4; half is yellow bar "other"

Recently when trying to update OS or apps on my iPhone 5s, 12GB, I've had to delete data such as music or photos because about half the capacity bar (near the sync button on the summery page) is filled with a yellow bar labeled "other." I have no idea what this is nor why it is there. Is there something I can do to lower or remove it? It isn't apps nor is it "documents and data" which also seems high, but it's only about 1 GB. Thanks,

Message was edited by: Alice Dubiel