An explorable area is your party's instance of a zone that lies between cities, outposts, and missions. Explorable areas are where most of the PvE content takes place (the other being missions). Mobs in explorable areas and missions are typically geared for a certain level of player. When you walk through an explorable area, the map shows you moving, creating a path of red dots which traces where you have already ventured during that particular journey.