To achieve observability across your stack, it's essential to collect and analyze telemetry data from multiple sources, including metrics, events, traces, and logs. New Relic Query Language (NRQL) allows you to connect and explore your data with subqueries, enabling more sophisticated queries across different data sources and time ranges. Subqueries can be used to associate app errors and performance, find trends in multiple time ranges, and connect transactions and spans. To use subqueries effectively, it's recommended to test them separately, understand their limitations, and upgrade your query experience with Data Plus. With the new subquery feature in NRQL, you can unlock more powerful queries and gain deeper insights into the health and performance of your apps and systems.