Monitoring (system supervision)
Monitoring continuously observes the vital signals of a platform: availability, latency, errors, certificates, expiry dates. It turns failures into early alerts rather than client-discovered incidents.
In practice
The minimal stack for any serious site: an external availability probe, real-user Core Web Vitals tracking, TLS and domain expiry alerts, application error logs. The alert must be actionable — who, what, where — or it joins the noise that eventually gets muted. Monitoring fewer things but always responding beats the reverse.