The memory device used by Desmond Miles in Assassin's Creed is the Animus.
The Animus is a fictional machine that lets a user experience genetic memories inherited from ancestors. In the first game, Abstergo Industries forces Desmond to enter the Animus so researchers can investigate his ancestor Altaïr Ibn-La'Ahad. The device provides the framework for moving between modern-day scenes and historical adventures.
The series later presents several versions and related systems. The Animus is used by characters including Lucy Stillman, Warren Vidic, and Layla Hassan, while the Helix becomes a later consumer-oriented entertainment platform associated with Abstergo. These devices serve similar memory-exploration purposes but are not interchangeable names for the original machine.
The Animus also explains why the games can portray historical events through a playable ancestor while retaining a modern protagonist. Its visual interface, synchronization system, and memory-sequence structure became defining features of the franchise. Eagle Vision is instead a special perception ability, and the Apple of Eden is a Piece of Eden.