Availability Zone, they run on their own physically distinct, independent infrastructure, and this is engineered in such a way that it can be highly reliable. Common points of failures like generators and cooling equipment are not shared across Availability Zones. Additionally, they are physically separate, such that even extremely uncommon disasters such as fires and flooding would only affect a single Availability Zone. Your data is also replicated to different AZ in-order to make it durable. This way AZ keeps your data safe and also private.