Alertmanager is an application that handles alerts sent by client applications such as Prometheus. It can also perform alert grouping, deduplication, silencing, inhibition. Definitely a useful addition to any modern monitoring infrastructure.
That being said, configuring it can be a little daunting with the many different configurations available and somewhat vague explanations on some of the terms.
While configuring Alertmanager, I came across these 3 confusing terms: group_wait, group_interval and repeat_interval.