The AWS Well-Architected Framework (WAF) is a set of best practices developed by AWS experts to help customers design, deploy, and manage their cloud applications efficiently and securely. The framework is based on six pillars: Operational Excellence, Security, Reliability, Performance Efficiency, Cost Optimization, and Sustainability, each offering in-depth guidance and compliance checklists. A key feature of WAF is the shared responsibility model, which outlines AWS's role in maintaining core infrastructure while customers are responsible for the resilience of their workloads. The Operational Excellence and Reliability pillars are crucial, emphasizing automation, incident response, and resilience against disruptions. The text highlights Gremlin's role in facilitating proactive testing of cloud application resilience through automated reliability tests, which simulate real-world conditions to ensure systems meet WAF standards. These tests allow teams to identify and address availability risks before they impact users, thereby enhancing the reliability and performance of cloud deployments.