This document discusses service monitoring, server monitoring, and custom monitoring using various tools. It introduces Pingdom and Pagerduty for service monitoring to check if a service is working. New Relic is presented for server monitoring of CPU, disk, memory, etc, with Slack/email for alerts. Custom monitoring with Datadog is also covered to define custom metrics and thresholds according to requirements, with Pagerduty/email for alerts. The presenter encourages not being afraid of monitoring and building it incrementally like Lego blocks while adapting to application changes.