Your collection is a term used to describe all of your NEON HOPE cards that are currently not in use for the current episode (meaning they are neither in play or out of play).

Your collection can include at maximum 1 copy of each NEON HOPE product.

In a campaign all players share 1 collection among them (no matter how many copies of NEON HOPE they actually possess among them). This also applies when building character decks. (See details under: Character Customization.)