Massive Multiplayer Online Role Playing Games or MMORPGs as they are more commonly known, are role playing games which bring together large numbers of players via the internet.
A defining feature of MMORPGs is that they all offer a persistent virtual world in which to play. These worlds often support thousands of simultaneous players, all of whom are playing a single character in the game.
What Does This Mean?
In a MMORPG you take control of a character (often known as an avatar) and guide its actions within the game. Most games offer an experience based level system a player guides their character through certain tasks, such as killing a monster, and in return their ability to repeat similar tasks increases. This is usually represented by an overall skill level associated to the character, and sub levels representing individual skills.
As the worlds are persistent your skills are saved, meaning that the time and effort invested into the game is permanently reflected in your character.
For example if you played a combat orientated game your overall ability to fight may be represented by a Combat Level this level would increase each time...