How do you ensure high availability in your applications and what coding techniques or tools have you implemented

Question

It is a question that reveals methods and practices that you use so that your applications don't go down and aren't momentarily taken down. It asks for actual coding techniques or tools you are utilizing to help boost high availability, perhaps load balancing, failover mechanisms, or redundancy. Indeed, it is aimed at gaining insights into the designs and implementations for systems that attain minimum downtime with predictable performance during peak traffic conditions or failure scenarios.