The primary difference between a Distributed Denial of Service (DDoS) attack and a Denial of Service (DoS) attack is in the source of the attack. ADDoSattack involves multiple compromised systems (often part of a botnet) attacking a single target, overwhelming it with traffic or requests. In contrast, aDoSattack typically involves a single source attacking the target. The goal of both attacks is to make a service unavailable, but DDoS attacks are usually more difficult to defend against because of their distributed nature.