Role-Playing Game

A role-playing game (RPG) is a game in which players assume the roles of characters in a fictional setting. Players take responsibility for acting out these roles within a narrative, either through literal acting or through a process of structured decision-making or character development. Actions taken within many games succeed or fail according to a formal system of rules and guidelines^.
There are several forms of RPG. The original form, sometimes called the tabletop RPG, is conducted through discussion, whereas in live action role-playing games (LARP) players physically perform their characters' actions. In both of these forms, an arranger called a game master (GM) usually decides on the rules and setting to be used and acts as referee, while each of the other players plays the role of a single character.
Several varieties of RPG also exist in electronic media, such as multi-player text-based MUDs and their graphics-based successors, massively multiplayer online role-playing games (MMORPGs). Role-playing games also include single-player offline role-playing video games in which players control a character or team who undertake quests, and may include capabilities that advance using statistical mechanics. These games often share settings and rules with tabletop RPGs, but emphasize character advancement more than collaborative storytelling.
Despite this variety of forms, some game forms such as trading card games and wargames that are related to role-playing games may not be included. Role-playing activity may sometimes be present in such games, but it is not the primary focus. The term is also sometimes used to describe roleplay simulation games and exercises used in teaching, training, and academic research.

Source: wikipedia