A Denial of Service (DoS) attack is a type of cyber attack in which the attacker attempts to make a network resource or website unavailable to users by overwhelming it with a flood of traffic or requests. This can be accomplished by using multiple computers or devices to send a large amount of traffic to the targeted resource, or by exploiting vulnerabilities in the software or hardware running the resource. The goal of a DoS attack is to disrupt normal traffic and make the targeted resource unavailable to legitimate users.