[Groxx]

The generating of new blocks is what sets the transaction "in stone". And the more blocks past a transaction's inclusion, the harder it is to reverse that transaction - more blocks = more certain you have actually received the money.

Prior to being included in a block, it's entirely possible for the payer to issue the same money to multiple recipients. Once it's in, it's assured that only one is included, and others are therefore invalid. So it's in recipients' best interests to wait for a few blocks before totally accepting something as "paid".

[shazow]

Ah that makes sense. Thanks for the explanation.