A 51% attack occurs when a single entity or group gains control of more than half of the computational power (hash rate) on a blockchain network. With majority control, the attacker can manipulate the blockchain by reversing transactions, double-spending coins, or preventing new transactions from being confirmed.
Such attacks undermine the trust and security of the network, potentially leading to financial losses and a loss of confidence among users. While large networks like Bitcoin are relatively resistant to 51% attacks due to their size and decentralization, smaller networks can be more vulnerable.
