Role Play is sort of an extended step from like when you were a kid and playing with your friends where one of you were a doctor and the other a nurse and one of your stuffed animals had like an illness or something. Obviously when you're eight years old you're not a real doctor you're pretending to be one but your personality and maybe your mannerisms might be different than how they normally would be. When it comes to games when they get the rpg label it stands for role playing game because you're loosely role playing as the main character. Then for mmo's some people will make up a different story than what the game gives them. Like they might have a Raen Au Ra who left their underwater home for adventure and wasn't ever the warrior of light for instance.