GlossaryAdvanced
51% Attack
A scenario where one party controls enough of a network to potentially manipulate its history.
A 51% attack describes a situation where a single miner or group controls more than half of a proof-of-work network's computing power, or an equivalent majority stake in a proof-of-stake network.
With that level of control, an attacker could potentially reverse their own recent transactions or block others from confirming, though rewriting deep history or creating new coins outside the protocol's rules generally remains impractical.
Examples
- Smaller networks with less total computing power or stake are generally more vulnerable to a 51% attack.
- A 51% attack is a risk cited when evaluating how decentralized and secure a given network actually is.