What is Monitoring
Watching a live system's health through metrics, dashboards, and alerts, so the team finds problems before users report them.
In plain terms
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.
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.
Related
Read the lesson on Monitoring More in Who does what on a team