A 25% attack occurs when a malicious entity controls at least 25% of the total hashing power or computing resources of a blockchain network. This level of power allows the attacker to influence the network’s operations significantly.While not enough to execute a full takeover, the attacker can launch double-spending attacks, where they can spend the same cryptocurrency twice. They can also prevent transactions from being confirmed, leading to a denial of service for legitimate users. The attack is a variation of the majority attack, where controlling more than 50% typically guarantees dominance over the network. In a less secure network, even a lower percentage can create chaos, making 25% of the hashing power a noteworthy threshold.Ultimately, this attack highlights the importance of decentralization and network security in maintaining trust and functionality in blockchain systems. Keeping the distribution of hashing power wide and diverse helps mitigate the risks associated with such attacks.