The Animus is the fictional technology that lets Assassin's Creed characters experience genetic memories.
In the series, a person enters an Animus machine and relives memories inherited through their DNA from ancestors. This device provides the narrative link between modern-day characters and historical protagonists such as Altaïr, Ezio, and Bayek.
Abstergo Industries develops and uses Animus technology in the modern-day storyline. The Assassin Brotherhood also uses related systems, including portable or modified versions. The concept allows the games to move between historical settings and a continuing contemporary conflict.
Helix is a separate Abstergo entertainment platform introduced in the series, not the generic name for the memory machine. Eagle Vision is a perception ability used by characters, while Abstergo is a corporation and Templar organization. These terms are related to the setting but are not synonyms for Animus.