OpenTelemetry is a collection of standards and tools to make it easy to get metrics, distributed traces, and logs out of applications. For example, OpenTelemetry's Java agent will instrument Java applications out-of-the-box, with no code change required. This talk shows how to use these signals for application monitoring. We will introduce Grafana's open source databases: Loki for logs, Tempo for traces, and Mimir for metrics. And we will show how to use Grafana to explore the telemetry data for an example application running on Kubernetes. Grafana and Prometheus metrics have been popular among platform engineers for monitoring Kubernetes clusters for a long time. This talk will show how application developers can benefit from Grafana as well, using open standards like OpenTelemetry, and open source monitoring backends like Loki, Tempo, and Mimir.