The terms monitoring and observability are often used interchangeably, but they represent fundamentally different approaches to understanding system behavior. Monitoring is the practice of tracking predefined metrics and alerting on threshold violations. Observability is the property of a system that makes it possible to understand its internal state from its external outputs — enabling you to diagnose issues you didn't anticipate.
The Three Pillars
Observability is typically described in terms of three signal types: metrics (quantitative measurements of system behavior over time), logs (timestamped records of discrete events), and traces (records of the path a request takes through a distributed system). Modern observability platforms — Datadog, Honeycomb, Grafana — bring these three signals together in unified interfaces.