Everybody knows about Apple iCloud backups — how to disable this feature, or (if you are on the other side) how to download the data.
However, iCloud is not just about backups. There is quite a lot of data that is also being *synced* across all the devices, and so stored in the iCloud — including contacts, calendars, notes, media files, documents, 3rd party application data, passwords, credit card numbers and much more (e.g. mail signatures and custom text shortcuts). Even if you disable syncing completely (but still have the iCloud completely), some data stil goes to Apple servers and so accessible by both Apple and probably 3rd parties (from hackers to government). Have I mentioned call logs? There is no such option to sync them, but it is still there.
You may think that using two-factor authentication makes your data safe, but in fact it does not. Even more, this “protection” make it *easier* to access some data, such as passwords and CC numbers. Come see how.