Proof of importance (Proof of Importance, PoI) is a consensus algorithm that determines a participant's contribution to the network based on several factors rather than only the size of their balance. In classic proof of stake, the decisive factor is the number of coins held, and this can encourage simply accumulating funds. PoI, on the other hand, tries to reward those who actually use the network and keep it alive.
The calculation of "importance" usually includes the size of the balance, the regularity and volume of transactions, and a participant's network connections — with whom and how actively they interact. Based on this data, a rating is built, and the higher it is, the greater the chance of earning the right to form a block and a reward. This approach encourages the circulation of coins within the project's economy rather than their passive storage.
The best-known implementation of proof of importance is used in the NEM network with its asset XEM. The algorithm was designed with resistance to artificial inflation of metrics in mind: a combination of related metrics is taken into account, so simply splitting funds or making fictitious transfers between one's own addresses does not provide an easy advantage. PoI is regarded as an attempt to make consensus more "fair" toward active users.
