This is an informal “test” of artificial intelligence, coined in a 1950 paper by mathematician and computer scientist Alan Turing.
The test is quite simple: a human interacts with someone/thing via written communication (chat, email, etc.). The other conversant is either another human, or an artificial intelligence. If the human misidentifies the computer as a human, the test is “won.”
Again, this is a very informal test, but the larger point Turing was making is that the most basic measure of a computer’s ability to imitate a human is if another human thinks it’s a human. If a human can’t distinguish AI from another human, then it may as well be human, regardless of any other method of measuring the value or power of it.
The Turing Test was originally called The Imitiation Game, which led to a 2014 movie of the same name about the life of Alan Turing (however, I saw the movie, and I remember it being much more about the Enigma code-breaking that about AI).
Of course, “AI” itself is a very general term. This page discusses multiple levels of AI, from tools designed to do specific things, through so-called “self-aware” and “general AI” (GAI) which is what we imagine when AI becomes “human”.
Self-Aware: These AI systems have a sense of self and consciousness. They are still in the theoretical stage and may never be possible to create. […]
General AI: These AI systems are capable of learning any intellectual task that a human can. They do not exist yet, but some researchers believe that they will be possible in the future. […]