It's the strangest thing. You've never traveled to Paris before, yet now that you're here, standing on a bridge spanning the Seine River, you distinctly remember being in this spot before. You can recall features of the bridge, and the curve of the river. You're likely going through déjà vu, a fleeting illusion that you've previously experienced something, when in reality you have not.
Déjà vu occurs because our minds are good at remembering objects, but not the placement or configuration of them. For example, it's relatively easy to notice that your colleague is wearing a pretty blue dress that your sister also owns. But let's say someone asks you to describe how the stalls are laid out at your local farmers' market. You might not be able to recollect that. Yet if you go to the art fair in a neighboring town and the vendors' booths are laid out in a similar configuration to those in your local farmers' market, you might get a feeling of familiarity. And if they're laid out in nearly the exact same fashion, you might feel that you've been to this art fair before. That's déjà vu [source: Markman].