” Déjà vu from French, literally “already seen”, is the phenomenon of having the feeling that the situation currently being experienced has already been experienced in the past. Déjà vu is a feeling of familiarity, and déjà vécu (the feeling of having “already lived through” something) is a feeling of recollection. Scientific approaches reject the explanation of déjà vu as “precognition” or “prophecy”, but rather explain it as an anomaly of memory, which creates a distinct impression that an experience is “being recalled”. This explanation is supported by the fact that the sense of “recollection” at the time is strong in most cases, but the circumstances of the “previous” experience (when, where, and how the earlier experience occurred) are uncertain or believed to be impossible. Two types of déjà vu are suggested to exist: the pathological type of déjà vu usually associated with epilepsy and the non-pathological which is a characteristic of healthy people and psychological phenomena.
A 2004 review claimed that approximately two-thirds of the population have had déjà vu experiences. Other studies confirm that déjà vu is a common experience in healthy individuals, with between 31% and 96% of individuals reporting it. Déjà vu experiences that are unusually prolonged or frequent, or in association with other symptoms such as hallucinations, may be an indicator of neurological or psychiatric illness.” https://en.wikipedia.org/wiki/D%C3%A9j%C3%A0_vu