The Animus is the fictional device used in Assassin’s Creed to relive ancestors’ experiences.
In the modern-day storyline, a person enters the Animus and accesses genetic memories inherited from an ancestor. Desmond Miles uses the machine to experience the lives of Altaïr, Ezio, and other historical figures. The device provides the narrative explanation for moving between modern scenes and historical gameplay.
The Apple of Eden is a powerful Isu artifact, not a memory machine. Eagle Vision is a special perception ability, and the Bleeding Effect is a side effect in which memories or skills from an ancestor begin influencing the user. These terms are all important to the franchise, but only Animus names the device.
The concept also supports the series’ fictional distinction between genetic memory and ordinary recorded history. Different Animus models appear throughout the franchise, including systems used by Abstergo Industries and later by the Assassin network.