In the Assassin's Creed franchise, the Animus is the fictional device that lets users experience genetic memories.
The Animus creates a virtual reconstruction of ancestral memories encoded in a person's DNA. This framing device allows modern characters to experience historical lives while keeping the story connected to a present-day conflict between the Assassins and Templars.
Desmond Miles is the first major modern character shown using the machine in the original games. Abstergo initially uses him to locate information about the Pieces of Eden, while later stories introduce different Animus models and users. The technology also supports gameplay features such as memory synchronization and historical simulation.
Helix is a related entertainment platform introduced in later games, not the general name of the memory machine. Eagle Vision is an Assassin ability for perceiving people and objects, and an Apple of Eden is a powerful Isu artifact.