Déjà vu (pronounced /ˈdeɪʒɑː ˈvuː/ ( listen) DAY-zhah VOO; French: [deʒa vy] ( listen), "already seen"; also called paramnesia, from Greek παρα "para," "near, against, contrary to" + μνήμη "mēmē," "memory") or promnesia, is the experience of feeling sure that one has witnessed or experienced a new situation previously (an individual feels as though an event has already happened or has happened in the recent past), although the exact circumstances of the previous encounter are uncertain. The term was coined by a French psychic researcher, Émile Boirac (1851–1917) in his book L'Avenir des sciences psychiques ("The Future of Psychic Sciences"), which expanded upon an essay he wrote while an undergraduate. The experience of déjà vu is usually accompanied by a compelling sense of familiarity, and also a sense of "eeriness," "strangeness," "weirdness," or what Sigmund Freud calls "the uncanny." The "previous" experience is most frequently attributed to a dream, although in some cases there is a firm sense that the experience has genuinely happened in the past.
The experience of déjà vu seems to be quite common among adults and children alike. References to the experience of déjà vu are found in literature of the past, indicating it is not a new phenomenon. It has been extremely difficult to evoke the déjà vu experience in laboratory settings, therefore making it a subject of few empirical studies. Certain researchers claim to have found ways to recreate this sensation using hypnosis. However, the subject of hypnosis is controversial in some circles, and such data would demand proof that hypnosis is possible as per the manner the study implies.
Retrieve from http://en.wikipedia.org/wiki/D%C3%A9j%C3%A0_vu
So if u have been through this before..don't worry it's normal ok..hehe..