A trigger is a starting point (an event) that starts a Zap. In Zapier, there are two kinds of triggers: polling and instant.  Zapier checks (polls) the app for data at regular intervals in the polling trigger. With the Free plan, the polling time is 15 minutes, while on the Team and Company plans, the time is one minute. In the instant trigger case, Zapier is notified instantly whenever there is new data in the app.