Prometheus
In plain terms
An open-source monitoring system and time-series database.
Going deeper
Prometheus scrapes and stores metrics, with a powerful query language (PromQL) and alerting, central to cloud-native monitoring. It pulls metrics on a schedule.
Under the hood
Pull-based scraping and PromQL drive flexible alerting; a CNCF project paired with Grafana.
Examples
Kubernetes monitoring, metrics, PromQL, alerting, Grafana, cloud-native.
Think of it like...
Like a tireless inspector regularly recording every system's vital readings.