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. It typically involves a large number of computers, called 'zombie' computers or bots, sending requests to the target website or network resource in order to overload it and prevent legitimate users from accessing it. The attacker hopes that this will cause the target site or network to crash or become unresponsive.