The type of cyberattack that involves overwhelming a system to render it unavailable is known as a Denial-of-Service (DoS) attack. This occurs when an attacker floods a network, server, or service with excessive traffic, causing it to slow down or crash. In some cases, techniques like Distributed Denial-of-Service (DDoS) attacks involve multiple compromised systems working in concert, making them even harder to mitigate. The primary goal of such attacks is to disrupt service accessibility for legitimate users, leading to significant financial and reputational damage for businesses.