Observability and incident response are crucial for minimizing downtime and ensuring reliable software systems, but resilience testing adds a necessary layer by proactively identifying potential points of failure within complex architectures. Resilience testing works in tandem with observability to monitor system metrics and uses techniques like Fault Injection to simulate problems, allowing teams to address issues before they cause outages. It also complements incident response by verifying system resilience to known failure conditions and refining alert systems, ensuring that only critical incidents trigger responses. Integrating these practices enhances systems' reliability and availability, helping organizations meet customer demands and operational goals.