Assassin's Creed II contains 100 collectible feathers for Ezio to find across its game world. The feathers are distributed through the game's Renaissance Italian locations and are intended as an optional exploration challenge rather than as required story objectives.
Collecting feathers connects to Ezio's family story. After the Auditore family's tragedy, Ezio can place feathers in a chest at the family villa in Monteriggioni. The activity rewards completionists with a special item and contributes to the game's broader collection and achievement systems.
The number is often confused with other Assassin's Creed collectibles, because later games use different totals and collection types. Assassin's Creed II also includes codex pages, statuettes, glyphs, and treasure, but those are separate activities. The total of 100 refers specifically to feathers, not to every collectible in the game.