What are Azure Availability Zones?

Azure Availability Zones are physically separate locations within an Azure region, each with independent power, cooling, and networking. They protect applications and data from data center failures. Each region with Availability Zone support has a minimum of three zones. Zone-redundant services like Azure SQL Database and Premium Blob Storage automatically replicate across zones. Zone-pinned resources like VMs deploy to a specific zone. To achieve high availability, deploy across multiple zones — if one zone fails, resources in other zones continue serving traffic. The SLA for VMs using Availability Zones is 99.99% (vs. 99.95% for VMs in an Availability Set). Availability Zones differ from Availability Sets (which protect from rack-level failures within a data center).