Definition
An Availability Zone (AZ) is a distinct physical location within a cloud provider's region designed for high availability and fault tolerance. Each AZ consists of one or more discrete data centers with redundant power, networking, and connectivity, isolated from failures in other AZs. Applications deployed across multiple AZs can automatically failover if one zone experiences an outage, ensuring continuous operation. This redundancy is crucial for business continuity, preventing service disruptions and data loss. For instance, deploying a web application's servers in two different AZs means that if one data center loses power, the other can continue serving traffic. Unlike a single data center, an AZ is a managed construct by the cloud provider, abstracting away the underlying infrastructure complexity. Understanding AZs is fundamental for cloud architecture and appears on exams like AWS Certified Solutions Architect Associate and (ISC)² CCSP.