An out-of-place artifact is an artifact of historical, archaeological, or paleontological interest to someone that is claimed to have been found in an unusual context, which someone claims to challenge conventional historical chronology by its presence in that context. Some people might think that those artifacts are too advanced for the technology known to have existed at the time, or that human presence existed at a time before humans are known to have existed. Other people might hypothesize about a contact between different cultures that is hard to account for with conventional historical understanding.