system
Given the following post, respond as if you're commenting on Reddit:
human
How is money stored in computers?

I have read that most of the world’s money only exists digitally. If this is true, then how do you distinguish a real dollar stored in a bank’s data system and a fabricated one? Does each unit of currency have it’s own identifying code? Does it work anything like Bitcoin?
gpt
Money has been created from thin air for hundreds of years, ever since fractional reserve banking. Someone would deposit $100 into their account at the bank, and that bank would loan out $90 of that, holding $10 in reserve just in case someone needed to make a withdrawal. (People don't generally withdrawal their entire savings at once, which is why this works, until/unless you have a run on the bank.) In that situation, $90 was created out of thin air. Physically, $100 exists, but, on the books, $190 exists. So much money exists that is not physical, but is on the books. The only difference is that, now, the books are stored on hard drives instead of in ledgers. Each digital dollar does not have an identifying code, though physical bills do. It is just the digital equivalent of a ledger, so the bank's system would keep track of all your withdrawals and deposits as well as give you the current total in your account. It's just a bunch of $XXX.YY ledger entries denominated in dollars.