Alert groups show grouped alerts from an Alertmanager instance. By default, alert rules are grouped by the label keys for the default policy in notification policies. Grouping common alert rules into a single alert group prevents duplicate alert rules from being fired.
1. Click **Groups** to view the list of existing groups.
1. From the **Alertmanager** dropdown, select an external Alertmanager as your data source. By default, the `Grafana` Alertmanager is selected.
1. From **Custom group by** dropdown, select a combination of labels to view a grouping other than the default. This is useful for debugging and verifying your grouping of notification policies.
If an alert does not contain labels specified either in the grouping of the default policy or the custom grouping, then the alert is added to a catch all group with a header of `No grouping`.