Why do we experience déjà vu, and what causes this strange feeling?

We feel déjà vu when our brain thinks it has seen something before, even though it hasn’t, like when you walk into a room and suddenly feel like you’ve been there a million times.

Your brain is always working hard to remember things. Sometimes, it gets confused between what’s happening now and what happened a little while ago. It's kind of like when you're playing with your toy car, if you stop for a moment and look at it again, it feels new even though it’s the same car.

Imagine you’re eating cereal in the morning, and then later that day, you walk into the kitchen again and suddenly feel like you've already eaten that cereal. Your brain thinks, "Wait, I just did this!" But actually, it was a little while ago.

It's like your brain had two copies of the same event, one from a few seconds ago, and one now, and they got mixed up! That’s why you feel like you’ve seen something before when you haven’t. It’s not magic, it's just your brain doing its best to remember everything!