Proof of Work (PoW) and Proof of Stake (PoS) are the two dominant ways a blockchain decides who gets to add the next block — and, by extension, how the network defends itself against attackers.
Proof of Work, briefly
In a PoW network like Bitcoin, "miners" compete to solve a computational puzzle using specialized hardware. Whoever solves it first gets to propose the next block and collects the block reward. Security comes from the sheer cost of hardware and electricity required to control enough of the network's computing power to cheat.
Proof of Stake, briefly
In a PoS network, the right to propose and validate blocks is tied to economic stake rather than computing power. Validators lock up (or have delegated to them) the network's native coin. If they act honestly, they earn rewards; on networks with slashing, if they act dishonestly or go offline for extended periods, they can lose part of their stake. Security comes from the cost of acquiring enough stake to attack the network — and the fact that an attack would likely crash the value of the very asset the attacker holds.
Energy use
This is the most publicized difference. PoW networks consume large amounts of electricity by design — that cost is what makes attacks expensive. PoS networks don't need that energy expenditure to achieve security, which is why Ethereum's move from PoW to PoS in 2022 reduced its estimated energy consumption by more than 99%.
Participation
Mining competitively at scale generally requires specialized hardware (ASICs or large GPU farms) and cheap electricity, which has pushed PoW mining toward large, capital-intensive operations. Staking has a lower technical barrier — many people participate simply by delegating coins from a regular wallet, without owning any special hardware themselves.
Variants of Proof of Stake
- Delegated Proof of Stake (DPoS) — token holders vote for a limited set of delegates or "Super Representatives" who produce blocks, common on networks like Tron.
- Nominated Proof of Stake (NPoS) — used by Polkadot and Kusama, where nominators back validators they trust and share in rewards and risk together.
- Liquid Proof of Stake — used by Tezos, where delegation doesn't require locking or transferring coins at all.
Neither is simply "better"
PoW has a longer track record and a very simple security model. PoS is far more energy-efficient and generally cheaper to participate in, but its security assumptions are newer and vary more between implementations. Most blockchains launched in the last several years use some form of PoS — which is also why staking, rather than mining, is the more common way to earn rewards on the majority of major tokens today.