Friend Codes are strings of twelve numbers used to allow access to another person's town during online play. A friend code looks like ####-####-####, (three sets of four digits, where #'s represent numbers. To get someone's friend code, the player must go to the Town Gate and talk to Copper. He or she then must select "Friend Code!" and Copper will assign a friend code.
Friend codes were introduced in Animal Crossing: Wild World and later used in Animal Crossing: City Folk and Animal Crossing: New Leaf. However, in all 3DS games, including New Leaf, the friend code system uses the friend code stored on the 3DS. Friend codes are not to be confused with Dream Addresses. The addresses are used for visiting a 'dream' version of another player's town. The visit occurs in the Dream Suite.