The Game Boy Player allows you to play Game Boy or Game Boy Advance games on a TV through the Nintendo GameCube - it attaches to the High Speed Port on the bottom of the GameCube and you can use the GameCube controller or any Game Boy Advance system as a controller.
The GB Player can be connected to other Game Boy systems for multi-player games and is compatible with all regular Game Boy, Game Boy Color and Game Boy Advance game paks, though it won't work with motion sensor or rumble feature game paks.
An extra port for Game Boy Advance Link Cable usage means you can hook up to your friends' Game Boy Advance systems for a multiplayer party with compatible games. And because the Game Boy Player plugs into the Hi-Speed Port on the bottom of the Nintendo GameCube, the Serial Ports are left free for your Nintendo GameCube Modem Adapter or Broadband Adapter.