Secrets abound in Dragon Age 3: Inquisition. This page lists the categories of hidden aspects in the game, such as Treasure Maps and Easter Eggs.
Some Secrets will lead you to valuable loot, such as the Treasure Maps, while others, like the Easter Eggs, are just there for fun.
Collections in Dragon Age: Inquisition are in-game items which provide lore details and flavor. You can find items from these Collections across Thedas and store them; some will trigger trophies and achievements.
Treasure Maps provide guides to finding hidden treasure chests, which can contain various loot and gear. This page lists all of the Treasure Maps by location, along with Maps and in-game images where possible.