Console is an internal command prompt of a game. It can be used to activate various game functions and to alter the game's settings. It also functions as a log that lists some of the previous game events and messages along with the commands that have been activated in it.
Classic Doom games and other games based on the Doom engine did not originally include a console. After the Doom source code was released the feature was implemented into various source ports. Doom 3 was the first official Doom series game that was released with a console feature.