Voice of customer
Event triggers
Fire on something your own site knows happened, which is usually a better moment than anything a generic trigger can detect.
An event trigger fires when your site emits an event you name. It is the most precise of the five, because it lets the survey follow something that actually happened rather than something the browser can infer.
The moments worth asking about are usually specific in exactly this way: a filter returned nothing, a payment method was rejected, a size was out of stock, a support widget was opened and closed again. None of those is a page view, a scroll depth or an exit, and asking about them at the right moment gets an answer with real information in it.
The event name is matched exactly, which is deliberate. Fuzzy matching on event names produces surveys that fire on things nobody intended, and the failure is silent because the survey looks like it is working.
It shares its plumbing with conversion tracking, so an event already flowing through your data layer for measurement can trigger a survey without anything new being emitted for it.