POI is the consensus algorithm used in NEM to determine who will calculate the next block. An account’s importance is determined by how many coins it contains and the number of transactions made to and from that account. POI is different from other initiatives which use a fee-sharing model that does not take into consideration one’s overall support of the network.
In some proof-of-stake systems a person only needs to have large amounts of coins to form a block; however, in NEM the transaction amount as well as support of the network become a factor. This has been designed to encourage users of NEM to not simply hold NEM but instead actively carry out transactions within the NEM ecosystem.