People prefer to this genre as MMOs in shorthand, frequently, as an abbreviation of MMORPG. Of course, there are entries that don't fit the mold -- Planetside makes no pretense of being an RPG, for instance, while Second Life is really a virtual environment rather than a game per se. But the roots of the term do define what most MMOs are fundamentally aiming at: being an RPG with a massive component of players. Which is ironic, because as We Fly Spitfires points out, they're not really RPGs at all. They feature the stats and the leveling, but nothing of the larger sense of place and story that the genre hails as its strengths.