Group

A group, also known as a probability group, is a value assigned to some items in and  that determines their rarity in a specific town. Furniture, clothing, wallpapers, carpets, and stationery from Tom Nook's store and the Able Sisters are assigned a group of A, B, or C, and in each town, one of the groups is common, one is uncommon, and one is rare. Which group is common, uncommon, and rare is assigned upon town creation, and it is different for each type of item. For example, Group A furniture may be common in a town, but Group A clothing may be rare in the same town.

Having high item luck, through fêng shui or Katrina, increases the chances of uncommon and rare items appearing. The chances of finding common, uncommon, and rare items begin at 60/35/5 at minimum luck, and eventually balance out to 33/33/33 at max luck. Additionally, some sources only contain items of a specific rarity.

In
The following sources in only contain items from a specific group:
 * The Lost & Found only contains items from the town's common group.
 * The clothing received by Gracie if the player fails to fully wash her car is always from the town's common group.
 * Balloons only contain items from the town's rare group.
 * The received on Sale Day only contains items from the town's rare group.

In
The following sources in only contain items from a specific group:
 * Balloons only contain items from the town's rare group.