In a massively multiplayer game, you're almost always surrounded by crowds of other people. Your fellow players cluster around mailboxes and crowd around questgivers. They race you to monsters you need to kill and herbs you need to pick. In short, they're everywhere -- an inescapable part of playing an MMO.
Well, mostly. The A.V. Club has put together a writeup on WoW's abandoned spaces -- and despite the day to day MMO crowds, there are a lot of them. Have you visited Shattrath lately? What about Dalaran? These old content hubs are now abandoned by players, only inhabited by NPCs and the occasional alt-leveler. In fact, there are plenty of zones in the game where you can find you're the only person there -- and when you aren't crowded in by people, you can take a moment to enjoy the solitude and all the game details you might miss if you were racing a druid to the nearest ore node.
It's feigned solitude -- the game's other players are just a zone or a whisper away -- but it still works for a change of pace. For more of this quiet musing, just head out to one of WoW's abandoned spaces yourself -- or read through the full article on the A.V. Club.