The product monitors multiple systems, from customer interactions on our web applications down to the database and all layers in between. RUM, APM, logging, and infrastructure monitoring are all surfaced into single dashboards.
We initially started with application logs and generated long-term business metrics out of critical logs. We have turned those metrics and logs into a collection of alerts integrated into our pager system. As we have evolved, we have also used APM and RUM data to trigger additional alerts.