A Console is used to send commands to a video game, traditionally a first-person shooter, in the form of text inside of a scrolling box. The Console was introduced in Quake III Arena as an interface designed to allow the user to input a console command, often with variables, in a form similar to the interface of the Windows 98 Operating System. Which some options are accessible via the graphical menus, the Console served the purpose of giving advanced users direct control over the game. Traditionally, the Console is activated by pressing the tilde (~) key.
Consoles also tend to give output information such as errors and warnings, the files executed by the program, version number, input devices, server information, and other technicalities. Many of these features are useful for debugging and configuration purposes.
For a full list of console commands, see the page Console Commands.