AWS Regions and Availability Zones

AWS has many data centres around the world.
Amazon has created AWS Regions in different countries and have setup data centres in these locations. There are usually two to three data centres grouped into a particular region.

Each region is completely independent of each other and communicate via the Public Internet.

A customer would choose to create their Amazon EC2 instances, for example, in a particular region that would be closest to where their clients will be accessing them.

Each data centre in a region is called an Availability Zone and are physically isolated from each other. They are isolated enough that should a major catastrophy occur in the location where a particular data centre resides, the other data centres in that region would be unaffected. The only exception would be if a moon sized object hit that region. If that happens, it would just be bad luck.

Each Availability Zone in a Region are linked via low-latency private network connections. This allows an infrastructure or cloud architect to design a highly available environment by distributing their server instances across multiple Availability Zones and also to replicate data or backups across Availability Zones.Whilst Amazon have created the infrastructure to support high availability, it is up to the cloud architects to make use of it. Putting servers in the cloud does not automatically ensure high availability.

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