After we process a payment, the transaction is placed in pending state. The amount wont be available to your account until the transaction is marked complete.
If a call back url is setup on your account, after every payment processed, we call the url with the transaction details, which you can use to update your order, e.g. mark an invoice as paid and update your database. An example is when you are selling music on your website, you might want to send a download link after a user makes a payment, or make the song available on the users account.
The table below shows the data that we send to your call back url.