Audience triggers let you trigger events when users match the definition of an audience and become members.
You can trigger events, for example, when users reach key milestones like initiating a certain number of sessions or reading a certain number of articles, or crossing key event thresholds.
You can analyze these events in your reports, and you can enable them as key events as with any other events.
In cases where audience conditions are fully satisfied by a single event, metadata from that event is copied to the triggered event. In cases where audience conditions are satisfied by multiple events, metadata from the last event is copied to the triggered event. Copied metadata includes timestamp and session information but does not include the page/screen associated with the event.
Create audience-trigger events
You can create up to 20 audience-trigger events per property.
To create a trigger event as you're building an audience:
- To the right of the condition builder, under "Audience trigger", click + Create new.
- Enter a name for the event.
- Select Log an additional event when audience membership refreshes if you want to trigger an event each time a user meets the audience criteria, even if they are already a member of that audience.
- Note: Users added to an audience list are evaluated against the audience criteria each time they visit your website or app. If these criteria are met and the Log an additional event when audience membership refreshes option is selected, the audience-trigger event will be triggered (up to one per day) regardless of the user’s current membership status.
- Click Save.
Example
Let’s say you have an audience that includes users when the purchase count is greater than or equal to 2 in the last 7 days. You then created an audience-trigger event named audience_trigger_purchase for this audience list.
Now, a user made 2 purchases on your website and returned 4 more times within 7 days without buying anything else.
In this example, the user would be added to your audience list and would have 2 purchase counts and one event count for audience_trigger_purchase. If the Log an additional event when audience membership refreshes was selected when you set up the audience-trigger event, the audience_trigger_purchase would have an event count of 5.
Edit / delete audience triggers
To edit an event, click 
To delete an event, click next to the event name.
Key event thresholds
You can trigger events for simple thresholds. For example, if the condition for your audience "High-value customers" defines members as users whose lifetime value is greater than 100, then each time a user meets that condition and becomes an audience member, you can trigger an event like new_high_value_customer.
You can also use these events as proxies for more complex key events, for example, if you define the audience "Frequent long-term guests" as
Event: booked_hotel Parameter: days_booked Parameter condition: > 13 days AND Event: booked_hotel Parameter: event_count Parameter condition: > 1 in any 60-day period
then anytime a user met those conditions, you could trigger an event like new_frequent_longterm.
By monitoring the count of those events, you can see the pace at which your audiences grow.