51% Attack
A 51% attack is when one actor controls more than half of a network's mining power (or staked value), letting them rewrite history — double-spend coins, re
A 51% attack is when one actor controls more than half of a network’s mining power (or staked value), letting them rewrite history — double-spend coins, reorder or censor transactions. It’s the theoretical ceiling on how decentralized a network must be.
Why it matters
The Nakamoto Coefficient is literally counting “how many actors could you team up to reach 51%?” High hash difficulty on a huge network like Bitcoin makes it impossible; small chains with thin hash power get 51%-attacked regularly. This is the single clearest exposure of a network’s real decentralization.
Related terms
consensus · block ·
nakamoto coefficient