A bot is a general term in gaming that is used to refer to a character controlled by a computer. In one sense, bots are all the non-player characters (NPCs) in a game, including those that fight alongside as well as against the gamer. However, the definition of bots has broadened to include gamers who employ third-party programs to control their characters.
Techopedia explains Bot
Bots are forbidden by most massively multiplayer online role-playing games (MMORPGs) and other competitive online games. This is because a gamer can use bots to continue to rack up experience and points when he or she is not at the computer.
That said, if we follow a more traditional definition of bots, they are actually essential to gaming. Having intelligent bots as competition or help in a game allows players to experience multi-player gameplay without being online. Some players prefer to play bots rather than real people, either to practice or because their connection and/or experience level doesn’t allow them to compete online.
This definition was written in the context of Gaming