Metagaming is the use of out-of-character knowledge in an in-character situation. A character played by a metagamer does not act in a way that reflects the character's in-game experiences and back-story. Examples of metagaming include: Adjusting a character's actions if the player has some foreknowledge of the long-term intentions of the gamemaster; Using certain types of attack or defense based on the strengths and weaknesses of a monster/other characters the character knows nothing of, for example a weakness to fire-based magic; Using knowledge of the game's mechanics to gain an advantage in the game; Deciding on a character's course of action based on how the game's mechanics will affect the outcome; Another form of metagaming occurs as a form of powergaming during character creation, when a player takes flaws or liabilities that they know the gamemaster is unlikely to fully exploit, thereby acquiring extra creation options without paying a corresponding penalty. (wikipedia)