Proof of Stake (PoS)

Proof of Stake (PoS) is a blockchain consensus mechanism where validators are selected to propose and attest to new blocks based on the amount of cryptocurrency they have staked — locked as collateral — rather than on computational work performed.

How it works

1. Validators deposit (stake) a minimum amount of the network's cryptocurrency to participate (e.g., 32 ETH on Ethereum).
2. The protocol selects validators to propose blocks, weighted by their stake size and randomness.
3. Other validators attest (vote) that the proposed block is valid.
4. The block is finalized and validators earn staking rewards.

Key differences from Proof of Work

	Proof of Work	Proof of Stake
Selection mechanism	Computational power (hashrate)	Staked coins
Hardware required	ASIC / GPU miners	Standard server or computer
Energy consumption	High	Minimal
Earning mechanism	Block rewards + fees	Staking rewards + fees
Entry barrier	Mining hardware cost	Minimum stake requirement

Slashing

Validators can be slashed — lose a portion of their stake — for malicious behavior such as double-signing blocks or being offline for extended periods. Slashing is the PoS equivalent of the economic cost miners bear in PoW (wasted electricity) for producing invalid blocks.

Notable PoS networks

• Ethereum — switched from PoW to PoS in September 2022 (The Merge). The transition ended ETH GPU mining.
• Cardano (ADA) — PoS from inception, using the Ouroboros protocol.
• Solana (SOL) — high-throughput PoS with delegated staking.

See also

• Proof of Work
• Ethereum
• Beacon Chain