Human: What is a "distributed denial of service attack"? Assistant: 
A Distributed Denial of Service (DDoS) attack is an attempt to make a website or network resource unavailable to its intended users by overwhelming it with traffic from multiple sources. This can be done in many ways, such as sending large numbers of requests to the target system, flooding it with data, or attempting to exhaust resources available on the target machine. The goal of these attacks is usually to prevent legitimate users from accessing the targeted services.