In Assassin's Creed, the fictional technology used to view ancestral memories is called the Animus.
The Animus allows a modern user to relive genetic memories inherited from an ancestor. In the first game, Desmond Miles is connected to the machine so Abstergo Industries can access the memories of his ancestor Altaïr Ibn-La'Ahad.
The device creates the series' dual structure: players experience historical missions while also returning to a modern-day storyline. Later games introduce different Animus models and related interfaces, but the core idea remains the same.
The Animus is not the same as Eagle Vision, which is an Assassin ability used to identify people and objects. It is also distinct from the Pieces of Eden, which are ancient artifacts that drive much of the franchise's conflict.