AWS HA Basics:

Unlike other technology infrastructure providers, each AWS Region has multiple AZs. As we’ve learned from running the leading cloud infrastructure technology platform since 2006, customers who care about the availability and performance of their applications want to deploy these applications across multiple AZs in the same region for fault tolerance and low latency. AZs are connected to each other with fast, private fiber-optic networking, enabling you to easily architect applications that automatically fail-over between AZs without interruption.

The AWS control plane (including APIs) and AWS Management Console are distributed across AWS Regions and utilize a multi-AZ architecture within each region to deliver resilience and ensure continuous availability. This ensures that customers avoid having a critical service dependency on a single data center. AWS can conduct maintenance activities without making any critical service temporarily unavailable to any customer.