The Apple of Eden is the powerful First Civilization artifact central to Assassin's Creed lore.
The Apples of Eden are Pieces of Eden, advanced devices created by the Isu, also called the First Civilization. Their abilities include influencing human perception and behavior, which helps explain why Assassins and Templars repeatedly struggle to control them.
The original game places one Apple at the center of Altaïr's mission. Later games reveal additional Apples and expand the mythology surrounding their creators, their relationship with humanity, and the catastrophic solar event that affected the ancient world.
The Apple is often confused with other Pieces of Eden, including the Staff, Swords, Shrouds, and Rings. “Apple of Eden” identifies a specific artifact type, while “Piece of Eden” is the broader category. Their powers are fictional and belong to the series' science-fiction mythology.