A trigger is whatever initiates a microinteraction. Manual triggers are user initiated, and can be a control, an icon, a form, or a voice, touch, or gestural command. System-initiated triggers happen when a certain set of conditions are met.
The time of day can have an impact on the kinds of triggers for the app. Example: Noon triggers lunchtime transitions.
Share this highlighthttp://www.safaribooksonline.com/a/microinteractions-full-color/77575/