Deja vu literally means already seen, everyone in there life must have experienced the deja vu a situation in which you feel like that you have already seen the current situation. When this happen you feel very light and everything around you looks very familiar. It cannot be predicted that which things or situation will act as the catalyst for deja vu. Usually deja vu last for few seconds though some can experience deja vu for longer duration. You will find a lot of information on the subject on ritanblogi.blogi.net/blog/
Different people have different theories in relation with Deja vu, some consider it as a part of extrasensory perception and for some it is a paranormal experience. It is a fact that science is still in research to find out why deja vu happen and how could details of the unseen so clearly marked?
There are even people who consider the deja vu as a part of information shared from the past life and this is a information due to reincarnation. Debate on this topic is still on and on the list of unexplained subjects of science deja vu is ranked first.