Déjà vu is the eerie feeling of having experienced something before, even when it's happening for the first time. It's estimated that 97% of people experience déjà vu at least once, with many encountering it regularly.

The term, meaning "already seen" in French, was coined by philosopher Emile Boirac in 1890. Though it feels like a memory mix-up, it's often considered a brain glitch.

Scientists suggest it occurs when two streams of awareness collide -when a current experience feels like a false recollection.

Déjà vu can also be triggered by factors such as stress, fatigue, or even excess dopamine. In those with neurological conditions like epilepsy or schizophrenia, it may be more frequent, as alterations in brain areas involved in memory processing are common.

While rare, frequent déjà vu episodes could signal neurological issues, and visiting a doctor might be advisable. For most, however, it's just a curious and fleeting experience.