outage

An outage is a period during which a service, system, or facility is unavailable or nonfunctional. Outages can affect electrical power, telecommunications, internet services, software applications, data centers, and broadcast systems. They may be planned for maintenance or upgrades or occur unexpectedly due to faults, disasters, or other disruptions.

Common types include power outages, where electricity is unavailable; network or connectivity outages, where access to networks or the internet is interrupted; service outages that affect a specific application or platform; data-center or cloud-service outages that disrupt hosted resources; and broadcast outages affecting media transmission. Outages can be total, affecting all users, or partial, impacting only some regions, services, or components.

Causes range from equipment failure, software or hardware malfunctions, and maintenance work to natural disasters, overloads, human error, cyberattacks, and cascading failures arising from dependent systems.

Outages are detected by monitoring systems, automated alerts, and user or customer reports. Restoration time is measured from the onset of the outage to full service restoration. Metrics commonly used include mean time to recovery (MTTR), duration of the outage, number of affected users, and the extent of service degradation.

Impacts vary but can include safety risks, economic losses, disruption of communications and critical infrastructure, and reputational damage for operators. Providers typically publish incident reports and may implement emergency procedures, communicate expected restoration times, and offer workarounds or credit where applicable.

Prevention relies on redundancy, failover mechanisms, robust maintenance programs, capacity planning, and incident response drills. Organizations employ backup power, diversified networks, and automatic rerouting to minimize outage duration and impact.