Fastly emphasizes the importance of resilience in content delivery networks (CDNs) to ensure reliable user experiences and protect businesses from revenue loss and brand erosion caused by latency and outages. The challenges of global content distribution, such as geographic latency, network congestion, single points of failure, and adversarial events like DDoS attacks, require a CDN to be robust and responsive. Fastly's approach to resilience involves core principles and technologies that enable fast and available content delivery, with observability being a foundational capability. This entails monitoring detailed metrics, logs, and traces to understand network behavior, diagnose issues, and facilitate proactive maintenance and rapid incident response. The substantial investment in observability infrastructure is justified by its role in maintaining system resilience, enabling data-driven capacity planning, and ensuring the network can adjust to changing conditions. Future discussions will delve into the specific pillars that support Fastly's resilient infrastructure, focusing on high availability, disruption resistance, and recovery strategies.