A DDoS (Distributed Denial of Service) attack is a malicious attempt to disrupt the normal functioning of a targeted server, service, or network by overwhelming it with a flood of traffic. In a DDoS attack, multiple compromised computers or devices, often part of a botnet, are used to send a massive volume of requests to the target, causing it to slow down or become unresponsive. The goal is to make the service unavailable to legitimate users, which can result in downtime, financial loss, and damage to reputation. DDoS attacks can vary in size, duration, and complexity, and they are often executed using various methods, such as volume-based attacks, protocol attacks, and application layer attacks.