Participants:
The participants in the games are divided between players, who control individual characters, and games masters (who may be represented in software for digital examples) who control the remainder of thegame world beyond the player characters. Players affect the evolution of the game world through the action of their characters.

Game Master:
At least one, but not all, of the participants has control over the game world beyond a single character. A term commonly used for this function is “game master”,although many others exist. The balance of power between players and game masters, andthe assignment of these roles, can vary, even within the playing of a single game session. Part of the game master function is typically to adjudicate on the rules of the game, although these rules need not be quantitative in any way or rely on any form of random resolution.