The Animus is the fictional machine that lets characters relive ancestral memories in Assassin's Creed.
In the series, the Animus reads genetic memories inherited through a person's bloodline and presents them as an interactive historical experience. Desmond Miles uses the machine to experience memories belonging to ancestors such as Altaïr and Ezio.
The device is central to the franchise's structure because it connects modern-day characters with historical protagonists. It also explains why the player can explore past events while the series continues a separate present-day storyline involving Abstergo and the Assassins.
The Animus is not a time machine: users do not physically travel into the past. The experience is a reconstruction of genetic memories, and later games introduce variations such as portable systems and entertainment versions. The term is often confused with the Helix, a later Abstergo product used to access historical simulations.