A hold? As in: "You cannot charge anything else to this account until we remove the hold" ????
Please educate me on this
I might have to use my credit card account that I only use for emergencies for the preorder.
It's called a "Preauthorization". It means that the total amount is "Reserved" from your credit limit, i.e. if your limit is $1,000 and there is a preauthorization for $250, then you can only spend an additional $750 - even though you haven't actually been "charged" yet.
For a credit card, the good news is that it doesn't actually hit your statement until the final charge is issued (or "Captured"). So you don't have to worry about interest, etc.
For a debit card, the bad news is that once it's preauthorized, those funds are basically locked out of your checking account immediately. Apple doesn't get the money yet, but you don't have access to it either. The money is still in your account (e.g. if you have interest checking, you'll still get interest on it) but you can't access it. From your perspective, it behaves as though it were charged immediately.