This chapter was packed with concepts of reacting to events that happen in your monitored environment. We learned to describe simple checks that define conditions that should be reacted to as trigger expressions. Triggers themselves have useful functionality with dependencies and we can make them depend on each other.
Another large concept was actions. Actions being the things controlling what is performed when a trigger fires, have a very wide range of things to configure at various levels, including conditions of various precision, message contents, and actual operations performed starting with simple e-mail sending, using custom scripts, and ending with the powerful remote command execution. We also learned about other things affecting actions, like user media configuration and user permissions.
Let's refresh our memory on what alerting related concepts are there:
trigger was a problem definition having a severity, with trigger expression containing information on calculations and...