The net result of transaction status is a failure as the payment processor declined the transaction even though your bank had approved it. This transaction will NOT show up on your credit card statement as it is declined by the payment processor. To your bank, they'll see this transaction as approved and will temporarily hold ("reserve") this money until the payment processor claims the money (which will never do as it declined the transaction), or a specific time elapses with no action from the payment processor which then releases the reserve. The time it will take to release the fund varies from banks to banks.
Pending transactions are charges that temporarily display on your account while being processed, and can also represent placeholder amounts - sometimes as low as $1.00.
Transactions will appear in your "Posted Activity" once finished processing.
You may see a different amount or description between pending and posted transactions, especially with gas station transactions
Pending transactions generally post within 3 day; however please allow up to 10 calendar days
Transactions made after business hours may list as pending until the next business day
Some transactions require preauthorization and may be listed as pending until authorized
Pending transactions can't be disputed until posted and can only be canceled by contacting the merchant directly
You can google to explain better - here is a great example : http://www.webtrafficexchange.com/declined-credit-card-transaction-appear-approved-bank