Availability zone

In cloud computing, an availability zone is a subset of an IT infrastructure system that shares no service-critical components (including power, cooling and access) with any other availability zone. Availability zones are typically geographically separated from one another, to prevent local disasters from acting on more than one availability zone.

Some service providers also make higher-level regional distinctions between availability zones, allowing service providers to mitigate even regional-level disasters such as earthquakes and forest fires.

Applications requiring high availability are typically implemented as distributed systems that span multiple availability zones.

Services offering distinct availability zones include Amazon Web Services, Microsoft Azure and Google Cloud.