I have had comments occassionally that it appears that I am charging a customer on the date the order is placed, and again when the order ships. I charge only when the order has been packed, shipping calculated, and the box is ready to go out the door. If you happen to notice duplicate charges on your credit card statement, please be assured that I am not charging you twice... below is an article I finally found to describe this situation.
Authorization hold (also card authorisation, preauthorization, or preauth) is the practice within the banking industry of authorizing electronic transactions done with a debit card or credit card and holding this balance as unavailable either until the merchant clears the transaction (also called settlement), or the hold "falls off." In the case of debit cards, authorization holds can fall off the account (thus rendering the balance available again) anywhere from 1–5 days after the transaction date depending on the bank's policy; in the case of credit cards, holds may last as long as 30 days, depending on the issuing bank.
Signature-based (non-PIN-based) credit and debit card transactions are a two-step process, consisting of an authorization and a settlement.
When a merchant swipes a customer's credit card, the credit card terminal connects to the merchant's acquirer, or credit card processor, which verifies that the customer's account is valid and that sufficient funds are available to cover the transaction's cost. At this step, the funds are "held" and deducted from the customer's credit limit (or bank balance, in the case of a debit card) but are not yet transferred to the merchant. At the end of the day, the merchant instructs the credit card machine to submit the finalized transactions to the acquirer in a "batch transfer," which begins the settlement process, where the funds are transferred from the customer's accounts to the merchant's accounts. Contrary to popular belief, this process is not instantaneous: the transaction may not appear on the customer's statement or online account activity for one to two days, and it can take up to three days for funds to be deposited in the merchant's account.
For example, if an individual has a credit limit of $100 and uses a credit card to make a purchase at a retail store for $30, then his available balance will immediately decrease to $70. This is because the merchant has obtained an authorization from the individual's bank by swiping the card through its credit card terminal. However, the actual balance with the bank is still $100, because the merchant has not actually collected the funds in question. The actual balance will not be reduced until the merchant submits their batch of transactions and the banking system transfers the funds.
When viewing an online banking website, authorization holds often appear in the "pending transactions" section of the balance sheet. As stated above, authorization holds only last for a fixed maximum period of time. So, if an individual made the $30 purchase listed above, and their bank only kept that authorization hold in place for 1 business day, then the individual would see the funds as a pending transaction for that first day. If the merchant failed to present the item for payment within that first day, the authorization hold would "fall off" and the funds would appear to be available again. If the merchant then presented the item for payment 2 days later, the $30 transaction would "reappear" and actually be debited from the account at that time.