Application Performance Monitoring - tools that track how well your application performs and where bottlenecks occur. Like having a fitness tracker for your software that shows which parts are working hard and which are slowing down.
APM tools like New Relic show you that your checkout page takes 3 seconds to load because of a slow database query, not because of network issues.
All provide application performance visibility (latency, errors, throughput) using telemetry like traces, metrics, and logs. Azure Application Insights and OCI APM are dedicated APM offerings; AWS Application Signals builds APM-style views on top of CloudWatch and OpenTelemetry; GCP’s APM capabilities are delivered through a set of observability products (Trace/Profiler/Error Reporting) integrated with Cloud Monitoring and Logging.