What are AWS Regions and Availability Zones? How do they work together?

Question

Accepted Answer

Regions and Availability Zones (AZs) are the physical building blocks of AWS's global infrastructure. Region — a geographically isolated area with multiple AZs (e.g., us-east-1 , eu-west-2 ). Data does not leave a Region unless you explicitly replicate it. Availability Zone — one or more discrete data centers within a Region, with redundant power, cooling, and networking. AZs are isolated from each other but interconnected via low-latency (<1 ms) fiber. Multi-AZ design — deploy across at least two AZs (e.g., RDS Multi-AZ, ALB across AZs) for high availability — survives a single data-center failure. Multi-Region — for disaster recovery, compliance, or global latency reduction. Rule of thumb: use Multi-AZ for HA, Multi-Region for DR. As of 2026, AWS has 33+ Regions and 100+ AZs. Multi-AZ for HA, Multi-Region for DR — that one line separates the levels. Drop the <1 ms inter-AZ latency stat to sound senior.