Within a region, there are multiple data centers. These data centers are grouped into availability zones. Each region consists of 3 availability zones. Each availability zone is independent of another availability zone in that region in terms of cooling, power, and networking. To create resilience within a region you should deploy your resources into multiple zones. Microsoft rolls out updates in one zone at a time. Some services are zonal which means you can specify which single zone the resource should be deployed to, for example, a virtual machine. The opposite are zone redundant services. They will automatically be deployed into all zones in that region.
Availability Zones 3️⃣