As with most mmo’s this aspect of the game is one of the single most important elements. Playing with others is what makes this type of game so popular, if this element did not exist then you might as well be playing a single player game. Conversation takes place in a number of ways through an in game chat system and a mail system. The mail system allows for offline messages and packages to be sent while the more important chat system allows players to talk to people around them or send a tell to a specific person. This element is the root of coordination and awareness for this type of game and lets players chat and relax while playing or simply allows for bragging rights in an online world.
The conversation allows for coordination in an online world and without either of these two most tasks would be doomed to failure outside of the solo content. A great and somewhat unique example to this game lies in the public quests. These are quests that run constantly and require people to participate to complete. You often need your typical tanks, your healers, and of course your dps. Parts are easy to do, say such as lighting kindling to burn the villagers alive in (yes, Destruction is actually evil unlike the emo forsaken and blood elves) while others need coordinated effort to live through like when the protectors of said town come in to try to save the day. Of course this goes into everything else such as the RvR scenarios when we need players to fight in a certain area or focus fire the healers down first.
Awareness is a key factor in the game play. Awareness of what other people are doing and how to react to them. This is important as coordination in an online anonymous world frequently fails, miserably. So for example in a RvR scenario you frequently need to gauge what your team mates are doing. The ones faltering on the front line are they going to hold or are they going to leave you to die instead of sticking it out long enough for our side to do damage. People do not like to die even if the penalty is light and cowardice is one of few aspects you need to be aware of. Beyond that you would need to watch what the npcs are doing, is it safe to walk past that wolves’ den or should you take the scenic route? All of these social aspects play a significant role in the game and is really the reason I believe most people play this type of game. Why play against a computer that has to cheat to win when you can play with other people varied in skill and reactions.