Our team designs highly available and fault-tolerant applications in Azure by leveraging Availability Zones (AZs) to distribute resources across multiple zones within a region. For critical applications, we ensure that key components like virtual machines, load balancers, and databases are deployed across at least two or more AZs, ensuring that if one AZ experiences a failure, the others can continue to serve traffic without disruption. For stateless services, we use Azure Load Balancer to automatically distribute traffic across instances in different AZs, ensuring consistent performance and minimizing downtime. For stateful services, we utilize Azure SQL Database with Zone-redundant configuration or Azure Storage with geo-replication, so data is automatically replicated across AZs, providing high availability and disaster recovery. Additionally, we integrate auto-scaling to dynamically adjust resources based on traffic demand, further improving both performance and availability. This multi-AZ strategy has significantly increased the resilience of our applications, ensuring minimal disruption during failures and maintaining high uptime.