A 51% attack is a type of attack on a blockchain network in which an individual or group of individuals control more than 51% of the network’s mining power or computational power.
With this level of control, the attacker (a malicious actor or group acting in concert) can control over 50% of the total mining power of the blockchain network and disrupt the integrity of the blockchain.
This way, they can prevent new transactions from being confirmed, reverse transactions that have already been completed, and prevent other miners from completing blocks.
This can allow the attacker to double-spend coins and effectively gain control of the network. Such attacks are considered to be a significant threat to the security and integrity of a blockchain network.
Broadly speaking, there are four types of 51% attacks – Dominating entity, Goldfinger attack, Takeover Attack, and Cartels.
« Back to Glossary Index