A distributed denial-of-service (DDoS) attack floods a target with traffic or repeated requests from many systems at once. The goal is not to steal data or break into accounts, but to exhaust bandwidth, servers, or application resources so legitimate users cannot reach the service. Because the attack comes from multiple sources, it can be harder to block than a single-source flood.
DDoS attacks matter because availability is a core security property: if a public website, login portal, or API is unreachable, the service has effectively been taken offline. In real attacks, defenders may use traffic filtering, rate limiting, upstream scrubbing, or rerouting to absorb the load and keep essential pages working. Even when systems remain intact, a DDoS event can disrupt operations, slow incident response, and erode trust in the service.