Effective Proof-of-Stake

Effective proof-of-stake (EPoS) is a variant of proof of stake introduced by the Harmony blockchain, which launched staking on its mainnet in 2020. Its goal is to stop a few large validators from gaining control while still letting many participants secure the network. Instead of counting each validator's full stake, EPoS calculates an "effective stake" that is held within a band around the median stake of the elected validators. A validator far above the median gains little extra voting power or reward from additional stake, which encourages delegators to spread their tokens across smaller validators. Harmony also lets validators run several keys across its shards, linking EPoS to sharding. The design is one example of the goals described under diversified proof of stake. Large holders can still split stake across multiple validators. Also see delegated proof of stake.