Datadog's Real User Monitoring (RUM) and Application Performance Monitoring (APM) enable full-stack visibility, allowing developers to investigate backend dependencies when troubleshooting frontend issues or track the source of database failures. RUM provides real-time insight into how users experience an application, while APM offers distributed tracing and key performance metrics. The integration between RUM and APM enables unified visibility across layers of a stack, providing rich context around problems and helping developers locate backend root causes more easily. By connecting frontend data with corresponding traces, developers can pinpoint issues, measure end-user impact, and debug the issue using full visibility into metrics, logs, network performance data, and code hotspots from within a single pane of glass.