The Animus is the fictional machine used to view ancestral memories in Assassin's Creed.
In the series, a person enters the Animus while it uses genetic memories inherited through their ancestry to reconstruct experiences of earlier relatives. This device allows modern-day characters and players to experience historical periods without treating the stories as ordinary time travel.
Abstergo is the corporation that develops and operates Animus technology in the series, not the machine's name. Helix is a later entertainment and research platform associated with Abstergo, while Eagle Vision is an Assassin ability for identifying people and objects.
The Animus also explains the series' transition between modern-day scenes and historical settings. Different games show changing versions of the technology, including portable units and more commercialized systems, while keeping the core idea of accessing genetic memories consistent.