Monitoring
Watching a live system's health through metrics, dashboards, and alerts, so the team finds problems before users report them.
What it tells you about a developer
A developer who has set up monitoring has owned software after launch, which is a different job from building it. They decided what healthy means for a system and what deserves waking someone up. That judgment comes from running services with real users, and it transfers cleanly between companies and tools.
Monitoring collects numbers from a running system: how fast pages load, how many requests fail, how full the servers are. Dashboards display the numbers, and alerts page a person when one crosses a threshold. Observability is the deeper version: enough recorded detail to answer new questions about why something broke. Common tools include Datadog, Grafana, and Prometheus.