Peercoin uses the setting of the age of the coin as part of the algorithm the probability of mining. In this system, the longer your Peercoins have been on your account (up to 90 days), the more power (coin age) they have to create a block. The act of "Meeting" the block requires the consumption of the dignity of the coin age, and the network determines the consensus by selecting the chain with the greatest total consumed coin age. When the Peercoin blocks are separated, the consumed coin age is returned back to the original block account.