Fi Packs are different groupings within the Fi App (Miniature Poodle, California, etc.).
Fi Packs are a fun way to enjoy some friendly competition and see how your dog's activity compares to other dogs within the Fi Community.
The Rank Tab shows the results of your dog's activity between the different categories of Fi Packs. See: Rank Tab
For more information on the Fi Packs your dog can join, see: What Fi Packs Can My Dog Join?