midBlockchain
Explain 51% Attacks.
Updated Apr 28, 2026
Short answer
PoW relies on computational energy (mining) to secure the network, while PoS relies on validators staking their own tokens.
Deep explanation
PoW (Bitcoin) requires miners to solve complex mathematical puzzles, leading to high energy consumption. PoS (Ethereum 2.0) selects validators based on the number of coins they hold and are willing to 'stake' as collateral. This significantly reduces energy use and changes the economic security model from 'capital expenditure on hardware' to 'capital lockup'.
Real-world example
Ethereum's transition from PoW to PoS reduced its energy consumption by 99.9%.
Common mistakes
- Assuming PoS is less secure simply because it doesn't use electricity, or confusing Gas Limit with Gas Price.
Follow-up questions
- What is 'Slashing' in PoS?
- Why is the EVM called 'Turing Complete'?