Adventures are broken down into encounters. Encounters are typically keyed to areas on a map that you have prepared. Encounters can also be designed in the form of if/then statements: “If the PCs wait outside the druid’s grove for more than an hour, then his three trained dire bears attack.” The encounters of an adventure are all linked in some way, whether in theme (all the encounters that occur as they travel from the City of Grey-hawk to the Crystalmist Mountains), location (all the encounters in the ruins of Castle Temerity), or events (all the encounters that occur as the PCs attempt to rescue the mayor’s son from Rahurg the ogre king).