Availability Zone

Regions are physical locations where AWS has its data centers. Having one data center in big region serving a large population is risky and impractical the users in that region would have very slow service. To solve this AWS came up with Availability Zones (AZ). These are separate data centers within the same region. They ensure high availability and fault tolerance. If there’s a power outage in one availability zone of the region, users can still use their resources in other zones, which are located in other parts of the region.