Files with the extension .KBN are 'key-binding' files utilised by the in-game chat program 'TeamSpeak'. TeamSpeak is 'Voice over IP' software primarily used by gamers to communicate with other players of the same team whilst playing multi-player games online.

.KBN files are used by TeamSpeak to hold information regarding keybinding i.e. the practise of assigning specific functions or shortcuts to specific keys or key-combinations.

e.g. the combination of holding down ' + M' = 'whisper to another player'.