Proof of Work
Proof of Work (PoW) is a consensus mechanism requiring validators (“miners”) to expend computational energy to solve a cryptographic puzzle before adding a block to the blockchain. The first miner to solve the puzzle broadcasts the block, earns the block reward, and the network moves on.
Key properties: Sybil-resistant (energy cost deters fake identities); energy-intensive; 51%-attack requires controlling majority of hash rate; battle-tested (Bitcoin has never been successfully attacked).
Vs. Proof of Stake: ethereum migrated from PoW to proof-of-stake in September 2022 (The Merge), reducing energy consumption by >99%. ethereum-classic retained PoW as part of its “code is law” philosophy.
Referenced in: ethereum-classic, coinmarketcap-2026-ethereum-classic