The fictional memory-viewing device in Assassin's Creed is called the Animus.
The Animus allows a modern user to experience genetic memories inherited from ancestors. In the first game, Desmond Miles is forced to use the machine so Abstergo Industries can investigate the life of his ancestor Altaïr Ibn-La'Ahad.
The device provides the series' central structure: historical adventures are presented as reconstructions viewed from the present day. This framework allows the games to move between different centuries and protagonists while retaining an ongoing modern storyline.
The Animus does not literally send a person into the past. It interprets ancestral memories through genetic material, according to the franchise's fictional technology. Other terms in the series, such as the Observatory and the Eye, refer to locations or artifacts rather than the machine used to access memories.