Have you ever been doing something or talking to someone and, suddenly, you get this weird sensation that you’ve seen or heard it before? Even though you know that what you’re seeing or hearing is happening right now for the first time, you still feel like it’s familiar and has occurred previously.

If you’re like most people, you’ve felt that way from time to time. Believe it or not, there’s a special name for that feeling. It’s called déjà vu.

Déjà vu is a French phrase that means “already seen.” It is used to describe the feeling you get when you’re sure that you’ve already experienced a current situation, even though you can’t quite remember the prior experience and may only be imagining it.

Déjà vu was a term used by Émile Boirac, a French psychic researcher, in his book called L’Avenir des Sciences Psychiques (“The Future of Psychic Sciences”). Experiencing déjà vu involves a strong sense of familiarity combined with an equally strong strange or eerie feeling.

Often people feeling déjà vu believe the previous experience occurred in a dream. In some cases, though, people feeling déjà vu firmly believe the past experience actually happened.

Is déjà vu a sixth sense or a glimpse into the future or the past? Not likely! Researchers believe the sensation of déjà vu is most likely just a trick our brains play on us, making us think that an experience we’re currently having is being remembered rather than occurring right now.

This explanation makes sense when you consider that experiencing déjà vu involves a strong sense of remembering something, yet the details of the supposed previous experience are often very fuzzy. This accounts for the strange and weird feeling that usually accompanies déjà vu.

The brain is also suspected to be the cause of a couple of related phenomena that also have French names. Jamais vu (“never seen”) is a term psychologists use to describe the weird or strange feeling a person gets when he or she encounters a familiar situation that nevertheless feels unfamiliar.

Jamais vu is sometimes called the opposite of déjà vu. Unlike déjà vu, jamais vu involves people feeling like they’ve never experienced a situation before, even though they rationally understand that they’ve certainly experienced the situation previously. Jamais vu is sometimes associated with amnesia, because a person, for example, might temporarily not recognize a person or place that they definitely know well.

Another related phenomenon is presque vu (“almost seen”). Presque vu is sometimes called “tip of the tongue.” It’s a situation in which you can’t remember a familiar word or name momentarily. You feel like the word or name is on the “tip of the tongue” and, with effort, you usually can remember it eventually.