Augmented Reality Cards (often abbreviated as AR Cards) are cards that come with the Nintendo 3DS console. Scanning the card with the 3DS camera will make something pop up onto the card on screen, depending on which card is used-- for example, using a card with Mario's picture on the front will make a figure of Mario will pop up onto the card.
The word "AR" stands for "Augmented Reality".
Nintendogs + Cats
Nintendogs + Cats features an in-game item called the AR Camera which enables the player to use the 3DS Camera and scan AR cards. The player's own pet will appear on the card that comes with Nintendogs + Cats when accessing the AR Camera. Using a card intended for a different game-- for example, a card with Link from Legend of Zelda on it-- will cause the pet to wear trademark clothing, like a Link hat. This is known to work for Pikmin cards as well.
The Obedience Trial contest utilizes the AR Card function. Players need to keep the camera focused on the card and use their commands to tell the pet what to do.
- Nintendogs+ Cats: "This curious camera lets your pets jump into the real world!"