51% Attack

A 51% attack occurs when a single group controls more than 50% of the nodes in a blockchain network. In such a case, the network’s consensus may no longer be sufficiently decentralized to be viable, leaving the blockchain vulnerable to manipulation. Attackers with more than 50% control over a blockchain may be able to halt, reverse, and duplicate new transactions, which would be disastrous for any blockchain. Notably, as a network grows larger, more decentralized, and more valuable, a 51% attack becomes more difficult and expensive.