Video game modding is the process of player and fan-authored alteration of a video game and is a sub-discipline of general modding. A set of modifications, commonly called a mod, either changes an existing game or adds new content, with a varying complexity. Modders, people who mod video games, can introduce a variety of changes to games, including altering graphics, fixing bugs, and adding unique gameplay elements, all extending the replay value and interest of the game. Modding a game can also be understood as the act of seeking and installing mods to the player's game. Modding uses third-party software, which distinguishes it from tweaking pre-existing settings and in-game creations.