What is Proof of Work?
Proof of Work (PoW) is a consensus mechanism where miners compete to solve complex mathematical puzzles to validate transactions and add new blocks, earning crypto rewards for their computational effort.
What is Proof of Work?
Proof of Work is the original blockchain consensus mechanism, used by Bitcoin. Miners expend computational energy to find a hash value below a target threshold, proving they performed "work." The first miner to succeed adds the next block and earns the block reward.
How Mining Works
Miners repeatedly hash block data with a changing nonce until the result meets the difficulty target. This requires significant hardware (ASICs for Bitcoin) and electricity. The difficulty adjusts every 2016 blocks (~2 weeks) to maintain a 10-minute block time.
Security Model
PoW is secured by economic incentive — attacking the network would require controlling 51% of hashrate, costing billions of dollars in hardware and energy. Attackers would earn less from attacking than from honest mining.
Environmental Concerns
Bitcoin's annual energy consumption rivals some countries. This criticism drove the shift to Proof of Stake for Ethereum and most newer blockchains, though Bitcoin's mining increasingly uses renewable energy.