MMORPG stands for Massive(ly) Mutliplayer Online Role Play(ing) Game and an MMORPG is simply a genre of computer game in which there are hundreds (usually thousands or even millions) of players from all across the world.
In most MMORPGs the player takes the role of his or her own character and must navigate some sort of world or realm in order to complete quests and tasks.
Usually these worlds will be persistent, hosted on a permanent server, and actions taken by the players will have an affect on the realm or world.
Thus making it interactive, even when the player is not playing the game. This is known as being “real time” and is how MMORPGs emulate the real world.
In one particular instance in World of Warcraft, an event occurred where a spell effect which lowered the players health slowly over time was spread from player to player.
The disease effect got out of hand and as players ran back to towns and cities the virus spread and became an epidemic.
Later, a patch was released to remedy the problem, but the community was shocked at how closely the behavior seen in the game resembled real life.