Learning path · Step 3 of 8
Consensus Mechanisms
How do thousands of strangers agree on one truth without trusting each other? Through consensus — the rules that govern which version of the chain wins.
Proof of Work
Miners compete to solve costly puzzles. The winner adds the next block and earns a reward. Used by Bitcoin. Secure but energy-intensive.
Proof of Stake
Validators are chosen based on staked collateral. Used by Ethereum post-Merge. Far more energy efficient than PoW.
Delegated PoS
Token holders vote for trusted delegates who validate on their behalf. Fast and efficient — used by EOS and Tron.
💡 Quick Check
Why can't an attacker simply rewrite Bitcoin's history?
Because transactions are encrypted with the user's password
Because they'd need to control more than 50% of all mining power simultaneously
Because Bitcoin transactions are deleted after 7 days
Because all nodes are controlled by one trusted authority
