The Animus is the fictional device that lets characters experience ancestral memories in Assassin's Creed.
In the series, the Animus uses a person's DNA to reconstruct memories inherited from ancestors. A modern user enters the machine and experiences a simulated version of an ancestor's life, allowing the story to shift between contemporary scenes and historical settings.
Desmond Miles is the best-known early user, experiencing the memories of Altaïr, Ezio, and other ancestors. Later games expand the concept through products such as the Helix, a consumer entertainment system based on Animus technology.
The Animus is not the same thing as an artifact such as the Apple of Eden. Apples are Pieces of Eden with extraordinary powers, while the Animus is a machine used to access genetic memories.