So far, we have covered how PromQL can be invaluable in querying the collected data, but when we require an expression to be continuously evaluated so that an event is triggered when a defined condition is met, we're promptly stepping into alerting. We explained how alerting is one of the components of monitoring in Chapter 1, Monitoring Fundamentals. To be clear, Prometheus is not responsible for issuing email, Slack, or any other forms of notification; that is the responsibility of another service. This service is typically Alertmanager, which we'll go over in Chapter 11, Understanding and Extending Alertmanager. Prometheus leverages the power of alerting rules to push alerts, which we'll be covering next.