An outage is a period when a system, service, or network is partially or fully unavailable to users. It can affect a single application, a regional link, or an entire infrastructure layer, and it may result from hardware failure, misconfiguration, overload, malware, or a deliberate cyberattack.
In cyber security, outages matter because availability is one of the core security goals. Attackers may cause outages through denial-of-service traffic, destructive malware, account abuse, or by disrupting critical dependencies such as identity, DNS, or network routing. Defenders focus on redundancy, segmentation, backups, monitoring, and incident response so service can be restored quickly and the blast radius stays small. Even without data theft, an outage can damage operations, trust, and business continuity.