A game mod, short for "modification," is a modification or alteration to a video game that changes the game in some way. Mods can range from small changes and tweaks to the game's mechanics or gameplay, to large-scale modifications that add entirely new content or features to the game. Game mods are often created by fans of the game and are usually available for download for free. A game trainer, on the other hand, is a software program that modifies the behavior of a video game, typically by adding cheats or altering the way the game is played. Game trainers are often used to enable players to cheat in single-player games, or to gain an advantage in multiplayer games. Some common features of game trainers include the ability to give the player infinite health, ammunition, or other resources, as well as the ability to unlock hidden levels or items in the game. Some game trainers may also allow players to modify the game's graphics or gameplay mechanics. While game mods and game trainers are both used to modify the behavior of a video game, they are used for different purposes and can have different effects on the game. Game mods are usually created by fans of the game and are intended to enhance or expand the gameplay experience, while game trainers are often used to enable cheating or to gain an unfair advantage over other players.