Some or many Areas have Events in them. Events are what drives an adventure forward. There are five kinds of events: Happenings, Dialogues, Plot Forks, Trials, and Battles. Each is triggered in some way, perhaps even by simply arriving in their Area. The adventure will describe how Events are triggered.
When an Event is triggered the GM tells the players what has happened. Until that time players are free to roleplay in an Area as they desire.