A double-spend attack occurs when a digital currency holder tries to spend the same coins more than once. This is possible because digital information can be easily copied. In a decentralized system, transactions are recorded on a public ledger, like a blockchain. Each transaction must be verified by the network. If someone attempts to double-spend, they can create two conflicting transactions, trying to send the same coins to two different recipients.To prevent this, many systems use a consensus mechanism, where nodes in the network work together to confirm and agree on the validity of transactions. If a double-spend attempt is detected, the network will reject one of the conflicting transactions. Attackers might try to exploit the time it takes for transactions to be confirmed. If they can get one transaction recorded quickly while keeping a second transaction hidden for a little longer, they might succeed. However, networks are designed to make double-spending difficult, ensuring trust and security among users.