Rules as written (RAW) are the formal rules of a role-playing game that are written in a rulebook (or supplement) and presented by the game designers.
Rules as written (RAW) are often contrasted with two different terms with the acronym RAI: rules as intended (by the game designers who have a broader grasp of design goals before writing the rules down) and rules as interpreted (by the players of games, based on the rules as written).