What causes deja vu and why does it feel so strange?

You get déjà vu when your brain thinks it has already seen or done something, even though it hasn’t, and that’s what makes it feel weird and familiar at the same time.

Your brain is like a detective who checks clues to figure out what's going on. Sometimes, when you're in a new place or doing something new, your brain gets confused between two different memories, it’s like mixing up two photos that look similar but aren't the same.

Imagine you’re eating your favorite snack, and suddenly you feel like you’ve already eaten this snack before, even though it's brand new. Your brain is trying to match what it sees and feels with a memory it thinks it has, but it’s not quite right yet.

It feels strange because your brain is saying, “Wait! I know this!” but then you realize, “No, I don’t.” That mix-up between what you're doing now and a similar thing from before makes déjà vu feel like a little mystery that happens inside your head, just like when you think you've seen a friend in the park, only to find out it was someone else wearing the same hat.