Popup Trigger
The condition that makes a popup appear: exit intent, a scroll depth, a time delay, or a click on a specific link.
A trigger is the "when" of a popup, separate from the "what." The same offer can perform very differently depending on whether it fires on page load, after 30 seconds, at 50% scroll depth, or on exit intent, because each trigger implies a different level of engagement from the visitor.
Page-load triggers get the most impressions and the lowest goodwill; a visitor who has not read anything yet has no context for your offer. Scroll-depth and time-delay triggers wait for a signal of real interest before asking for anything.
Exit-intent is the least intrusive of the common triggers, since by definition the visitor was already leaving, so there is nothing left to interrupt. It is also the only common trigger unavailable on mobile in its literal form, where "leaving" is detected through scroll-up speed or back-navigation instead of cursor movement.
See it in practice