LOL, thanks!

Happy to help. I've actually posted a similar post a couple other times (I think in one or two of the car rental fora), but I think this one was the most intricate of them.

Credit card processing is confusing for the modern layperson. You have to remember that the way credit cards are processed now is still very much like what they were processed 30 years ago--except that electronic steps have replaced some of the manual steps. Things are still handled in batches (that in some cases take a few days to process), NOT real-time like many believe. Take a look at the following comparison:

Step 1: Authorization
OLD: Merchant calls authorization center [if transaction above floor amount] to obtain an authorization code
NEW: Merchant's POS terminal obtains an authorization code electronically

Step 2: End-of-day batch
OLD: Merchant submits credit card draft receipts (yes, the ones the merchant would use a roller to imprint the card onto) to his ["acquiring"] bank, either in person or by mail
NEW: Merchant submits credit card draft data to his ["acquiring"] bank electronically

Step 3: Fund transfer
OLD: Acquring bank requests and transfers funds from card-issuing banks via physical courier, mail, or telex
NEW: Acquiring bank requests and transfers funds from card-issuing banks via ACH (takes 2-3 days for net settlement to occur)

While in the old days, it could take a week or two for a merchant to receive payment, the new system is really not that much faster: it's still 3-5 business days for a merchant to see a deposit in his/her account. It is NOT instantaneous as many would believe. It's also why refunds tend to take awhile to post: the merchant uploads the refund transactions as part of the end-of-day batch, and it takes the banks at least 2-3 days to process the ACH transfer, plus some time on the book-ends for processing from the acquiring bank and card-issuing bank.

I don't pretend to be an absolute expert on this material--this is just what I've gleaned from watching how our systems work, doing some experimentation, and doing a TON of Google searching (these kinds of processes interest me greatly). But it's my nature to share information I've learned, so I hope I can be helpful to some people interested in such things. Of course, sometimes I get a bit carried away and long-winded, and I've put a lot of work into some threads that get buried under the archives of time. I wish I could search for all posts by me with more than, say, 500 words. Maybe I need to start maintaining a "Consolidated List of jackal's Informative Posts"!