The e-Reader is the accessory that lets the GameCube version of Animal Crossing scan themed cards.
Nintendo’s e-Reader was a Game Boy Advance add-on with a built-in scanner for cards printed with encoded dot patterns. When connected to the GameCube through a Game Boy Advance link cable, it could work with Animal Crossing’s Post Office. Scanned Animal Crossing cards could award furniture and other items, unlock town tunes, or provide new pattern designs.
The accessory is easy to confuse with other Nintendo peripherals. The GBA Wireless Adapter was used for wireless communication in compatible games, while the Rumble Pak was a vibration accessory for Nintendo 64 controllers. Wii Speak belonged to the later Wii-era Animal Crossing: City Folk and enabled voice chat. The e-Reader setup instead depended on a wired GameCube–GBA connection and specially printed cards.
The e-Reader launched in Japan in December 2001 and in North America in September 2002. Its Animal Crossing card support helped link the console game with Nintendo’s handheld hardware.