Déjà vu is the feeling that one has lived through the present situation before. Although some interpret déjà vu in a paranormal context, mainstream scientific approaches reject the explanation of déjà vu as "precognition" or "prophecy".

Why does déjà vu happen?

If your first view of something, like the view from a hillside, didn't involve your complete attention, you might believe you're seeing it for the first time. But your brain recalls the previous perception, even if you didn't have total awareness of what you were observing. So, you experience déjà vu.

Is déjà vu good or bad?

Déjà vu is French for "already seen," and it's just that - a sensation that something you're experiencing is something you've already experienced. ... And, Moulin said, deja vu is just your brain fact-checking that information. "It's a sign that something's going on that's healthy.